Sending e-mails with Postfix

In this recipe, we will set up Postfix Mail Transfer Agent (MTA). This will be a very basic setup which will enable us to send and receive e-mails from our server. Postfix is an open source MTA which routes e-mails to their destination. It is a default MTA for Ubuntu and is available in Ubuntu's main package repository.

Getting ready

You will need access to a root account or an account with sudo privileges.

A domain name (FQDN) is required while configuring Postfix. You can configure your local server for testing, but make sure that you set the proper host entries and hostname.

How to do it…

Follow these steps to send e-mails with Postfix:

Install Postfix and mailutils with the following commands:

$ sudo apt-get update
$ sudo apt-get install postfix mailutils -y

The installation process will prompt you to enter some basic configuration details. When asked for General type of mail configuration:, select Internet Site and then click on <Ok>:
On the next screen, enter your domain name, for example, mail.example.com, and answer the other questions. You can leave them with default values:
After installation completes, we need to modify the Postfix configuration under /etc/postfix/main.cf:
```
$ sudo nano /etc/postfix/main.cf
```
Set myhostname to point to your domain name:
```
myhostname = mail.example.com
```
Ensure mynetworks is set to the local network. This will secure your server from spammers:
```
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
```

Also check mydestination. It should contain your domain name:

mydestination = example.com, ubuntu, localhost.localdoma
in, localhost

Change the mail storage format to Maildir from the default mbox. Search and uncomment the following line:
```
home_mailbox = Maildir/
```
Optionally, you can change the TLS keys used by Postfix. Find the TLS parameters section and point the variables to your key path:
Save the configuration file and exit.
Now, reload Postfix for the changes to take effect:
```
$ sudo service postfix reload
```
Test if everything is working as expected. Open a telnet connection to the mail server:
```
$ telnet localhost 25
```
You should see an output similar to the following screenshot:
Now, send your first e-mail from this server. Type sendmail user@domain and press Enter. Then, type your message, and when done with that press Ctrl + D to send an e-mail.
To read your e-mails, log in with the user you send e-mails to. Start the mail program with the command mail. This should show you a list of e-mails received by this user account. The output should look similar to following screenshot:
To read any e-mail, type in the mail number and press Enter. Type q followed by Enter to quit the mail reader.

How it works…

Postfix installation is quite a simple task; you need to be sure that you have configured the proper settings and then you are up and running in minutes. The Postfix installation process itself prompts for basic settings.

Tip

If you miss providing configuration during installation, you can always recall the same dialogue box with the reconfigure command as follows:

$ sudo dpkg-reconfigure postfix

Other parameters include mynetworks and mydestination. With mynetwork, we have restricted the uses of the mail server to the local network. Only users on the local network can use this server to send and receive e-mails. The parameter mydestination specifies the domain names that Postfix is going to serve. For all other domains that are not listed under mydestination, Postfix will simply act as a forwarder.

We have configured Postfix to use the Maildir format for storing e-mails. This is a new storage format and provides various improvements over the default format, mbox. Also, Maildir is used by various IMAP and POP servers. With Maildir, each new message is stored in a separate file. This avoids file locking when working with messages and provides protection against mailbox corruption.

Now if you send an e-mail to a local domain, it will be delivered to the inbox of the respective user, which can be read with mail command. If you send e-mails to an external mail server, such as Gmail, chances are your mail gets delivered to spam. You need to include a number of different parameters in your e-mail headers and then make sure that your server IP is not blacklisted. It would be a good idea to use an external mail server such as Mail Chimp or Gmail for sending e-mails.

Getting ready

You will need access to a root account or an account with sudo privileges.

A domain name (FQDN) is required while configuring Postfix. You can configure your local server for testing, but make sure that you set the proper host entries and hostname.

How to do it…

Follow these steps to send e-mails with Postfix:

Install Postfix and mailutils with the following commands:

$ sudo apt-get update
$ sudo apt-get install postfix mailutils -y

The installation process will prompt you to enter some basic configuration details. When asked for General type of mail configuration:, select Internet Site and then click on <Ok>:
On the next screen, enter your domain name, for example, mail.example.com, and answer the other questions. You can leave them with default values:
After installation completes, we need to modify the Postfix configuration under /etc/postfix/main.cf:
```
$ sudo nano /etc/postfix/main.cf
```
Set myhostname to point to your domain name:
```
myhostname = mail.example.com
```
Ensure mynetworks is set to the local network. This will secure your server from spammers:
```
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
```

Also check mydestination. It should contain your domain name:

mydestination = example.com, ubuntu, localhost.localdoma
in, localhost

Change the mail storage format to Maildir from the default mbox. Search and uncomment the following line:
```
home_mailbox = Maildir/
```
Optionally, you can change the TLS keys used by Postfix. Find the TLS parameters section and point the variables to your key path:
Save the configuration file and exit.
Now, reload Postfix for the changes to take effect:
```
$ sudo service postfix reload
```
Test if everything is working as expected. Open a telnet connection to the mail server:
```
$ telnet localhost 25
```
You should see an output similar to the following screenshot:
Now, send your first e-mail from this server. Type sendmail user@domain and press Enter. Then, type your message, and when done with that press Ctrl + D to send an e-mail.
To read your e-mails, log in with the user you send e-mails to. Start the mail program with the command mail. This should show you a list of e-mails received by this user account. The output should look similar to following screenshot:
To read any e-mail, type in the mail number and press Enter. Type q followed by Enter to quit the mail reader.

How it works…

Postfix installation is quite a simple task; you need to be sure that you have configured the proper settings and then you are up and running in minutes. The Postfix installation process itself prompts for basic settings.

Tip

If you miss providing configuration during installation, you can always recall the same dialogue box with the reconfigure command as follows:

$ sudo dpkg-reconfigure postfix

Other parameters include mynetworks and mydestination. With mynetwork, we have restricted the uses of the mail server to the local network. Only users on the local network can use this server to send and receive e-mails. The parameter mydestination specifies the domain names that Postfix is going to serve. For all other domains that are not listed under mydestination, Postfix will simply act as a forwarder.

We have configured Postfix to use the Maildir format for storing e-mails. This is a new storage format and provides various improvements over the default format, mbox. Also, Maildir is used by various IMAP and POP servers. With Maildir, each new message is stored in a separate file. This avoids file locking when working with messages and provides protection against mailbox corruption.

Now if you send an e-mail to a local domain, it will be delivered to the inbox of the respective user, which can be read with mail command. If you send e-mails to an external mail server, such as Gmail, chances are your mail gets delivered to spam. You need to include a number of different parameters in your e-mail headers and then make sure that your server IP is not blacklisted. It would be a good idea to use an external mail server such as Mail Chimp or Gmail for sending e-mails.

How to do it…

Follow these steps to send e-mails with Postfix:

Install Postfix and mailutils with the following commands:

$ sudo apt-get update
$ sudo apt-get install postfix mailutils -y

The installation process will prompt you to enter some basic configuration details. When asked for General type of mail configuration:, select Internet Site and then click on <Ok>:
On the next screen, enter your domain name, for example, mail.example.com, and answer the other questions. You can leave them with default values:
After installation completes, we need to modify the Postfix configuration under /etc/postfix/main.cf:
```
$ sudo nano /etc/postfix/main.cf
```
Set myhostname to point to your domain name:
```
myhostname = mail.example.com
```
Ensure mynetworks is set to the local network. This will secure your server from spammers:
```
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
```

Also check mydestination. It should contain your domain name:

mydestination = example.com, ubuntu, localhost.localdoma
in, localhost

Change the mail storage format to Maildir from the default mbox. Search and uncomment the following line:
```
home_mailbox = Maildir/
```
Optionally, you can change the TLS keys used by Postfix. Find the TLS parameters section and point the variables to your key path:
Save the configuration file and exit.
Now, reload Postfix for the changes to take effect:
```
$ sudo service postfix reload
```
Test if everything is working as expected. Open a telnet connection to the mail server:
```
$ telnet localhost 25
```
You should see an output similar to the following screenshot:
Now, send your first e-mail from this server. Type sendmail user@domain and press Enter. Then, type your message, and when done with that press Ctrl + D to send an e-mail.
To read your e-mails, log in with the user you send e-mails to. Start the mail program with the command mail. This should show you a list of e-mails received by this user account. The output should look similar to following screenshot:
To read any e-mail, type in the mail number and press Enter. Type q followed by Enter to quit the mail reader.

How it works…

Postfix installation is quite a simple task; you need to be sure that you have configured the proper settings and then you are up and running in minutes. The Postfix installation process itself prompts for basic settings.

Tip

If you miss providing configuration during installation, you can always recall the same dialogue box with the reconfigure command as follows:

$ sudo dpkg-reconfigure postfix

Other parameters include mynetworks and mydestination. With mynetwork, we have restricted the uses of the mail server to the local network. Only users on the local network can use this server to send and receive e-mails. The parameter mydestination specifies the domain names that Postfix is going to serve. For all other domains that are not listed under mydestination, Postfix will simply act as a forwarder.

We have configured Postfix to use the Maildir format for storing e-mails. This is a new storage format and provides various improvements over the default format, mbox. Also, Maildir is used by various IMAP and POP servers. With Maildir, each new message is stored in a separate file. This avoids file locking when working with messages and provides protection against mailbox corruption.

Now if you send an e-mail to a local domain, it will be delivered to the inbox of the respective user, which can be read with mail command. If you send e-mails to an external mail server, such as Gmail, chances are your mail gets delivered to spam. You need to include a number of different parameters in your e-mail headers and then make sure that your server IP is not blacklisted. It would be a good idea to use an external mail server such as Mail Chimp or Gmail for sending e-mails.

How it works…

Postfix installation is quite a simple task; you need to be sure that you have configured the proper settings and then you are up and running in minutes. The Postfix installation process itself prompts for basic settings.

Tip

If you miss providing configuration during installation, you can always recall the same dialogue box with the reconfigure command as follows:

$ sudo dpkg-reconfigure postfix

Other parameters include mynetworks and mydestination. With mynetwork, we have restricted the uses of the mail server to the local network. Only users on the local network can use this server to send and receive e-mails. The parameter mydestination specifies the domain names that Postfix is going to serve. For all other domains that are not listed under mydestination, Postfix will simply act as a forwarder.

We have configured Postfix to use the Maildir format for storing e-mails. This is a new storage format and provides various improvements over the default format, mbox. Also, Maildir is used by various IMAP and POP servers. With Maildir, each new message is stored in a separate file. This avoids file locking when working with messages and provides protection against mailbox corruption.

Now if you send an e-mail to a local domain, it will be delivered to the inbox of the respective user, which can be read with mail command. If you send e-mails to an external mail server, such as Gmail, chances are your mail gets delivered to spam. You need to include a number of different parameters in your e-mail headers and then make sure that your server IP is not blacklisted. It would be a good idea to use an external mail server such as Mail Chimp or Gmail for sending e-mails.

Enabling IMAP and POP3 with Dovecot

In this recipe, we will learn how to install and set up Dovecot to enable accessing e-mails over IMAP and POP3 protocols. This will enable mail clients such as thunderbird to download e-mails on a user's local system.

Getting ready

You will need access to a root account or an account with sudo privileges

Make sure that you have set up Postfix and are able to send and receive e-mails on your server.

You may need an e-mail client to connect to and test the Dovecot setup.

How to do it…

Follow these steps to enable IMAP and POP3 with Dovecot:

First, install the Dovecot binaries from the Ubuntu main repository:

$ sudo apt-get update
$ sudo apt-get install dovecot-imapd dovecot-pop3d

You will be prompted for a hostname to be used for certificate generation. Type in a full hostname, for example mail.example.com. You can skip this step if you already have certificates.
Next, proceed with configuring Dovecot. Open the file /etc/dovecot/dovecot.conf:
```
$ sudo nano /etc/dovecot/dovecot.conf
```
Find the Enable installed protocols section and add a new line to set the protocols that you want Dovecot to support:
```
protocols = pop3 pop3s imap imaps
```
Open /etc/dovecot/conf.d/10-mail.conf and set the mailbox to be used. Dovecot supports mbox as well as Maildir. Make sure you set the correct path of your mail directory:
```
mail_location = mbox:~/mail:INBOX=/var/spool/mail/%u
```
Open /etc/dovecot/conf.d/10-ssl.conf and uncomment or change the following lines to enable SSL authentication. Here, I have used certificates created by Postfix. You can use your own certificates or use the one generated by Dovecot:
```
ssl = yes
ssl_cert = < /etc/ssl/certs/ssl-cert-snakeoil.pem
ssl_key =</etc/ssl/private/ssl-cert-snakeoil.key
```
Restart the Dovecot daemon:
```
$ sudo service dovecot restart
```
Test Dovecot by creating a telnet connection. You should see an output similar to the following:
```
$ telnet localhost pop3
```

How it works…

Dovecot is one of the most popular Mail Delivery Agents (MDA) with support for IMAP and POP3 protocols. It works with both major mailbox formats, namely mbox and Maildir. The installation process is simple, and a minimal configuration can get you started with your own IMAP or POP3 service.

Dovecot developers have tried to simplify the configuration by separating it across various small files for each section. All these configuration files are located under /etc/dovecot/conf.d. If you prefer to use a single configuration file, you can replace the default file with the entire working configuration. To get all enabled configurations, use the doveconf -n command:

# mv /etc/dovecot/dovecot.conf /etc/dovecot/dovecot.conf.old
# doveconf -n > /etc/dovecot/dovecot.conf

In this recipe, we have configured Dovecot to support POP3, POP3 secure, IMAP, and IMAP secure. You can choose a single protocol or any combination of them. After setting protocol support, we have set the mailbox type to mbox. If you are using Maildir as your mailbox format, instead replace the mailbox setting with following line:

mail_location = maildir:~/Maildir

Now, when a user wants to check his e-mails, they need to authenticate with the Dovecot server. At this stage, only users with a user account on the server will be able to access their e-mails with Dovecot. To support users without creating a user account, we will need to set up Virtual Users, which is covered in the next recipes.

If you plan to skip SSL setup, you may need to enable plain text authentication under the configuration file, /etc/dovecot/conf.d/10-auth.conf. Find and uncomment the following line and set it to no:

disable_plaintext_auth = yes

The default setting is to allow plain text authentication over SSL connections only. That means the clients that do not support SSL will not be allowed to log in.

Getting ready

You will need access to a root account or an account with sudo privileges

Make sure that you have set up Postfix and are able to send and receive e-mails on your server.

You may need an e-mail client to connect to and test the Dovecot setup.

How to do it…

Follow these steps to enable IMAP and POP3 with Dovecot:

First, install the Dovecot binaries from the Ubuntu main repository:

$ sudo apt-get update
$ sudo apt-get install dovecot-imapd dovecot-pop3d

You will be prompted for a hostname to be used for certificate generation. Type in a full hostname, for example mail.example.com. You can skip this step if you already have certificates.
Next, proceed with configuring Dovecot. Open the file /etc/dovecot/dovecot.conf:
```
$ sudo nano /etc/dovecot/dovecot.conf
```
Find the Enable installed protocols section and add a new line to set the protocols that you want Dovecot to support:
```
protocols = pop3 pop3s imap imaps
```
Open /etc/dovecot/conf.d/10-mail.conf and set the mailbox to be used. Dovecot supports mbox as well as Maildir. Make sure you set the correct path of your mail directory:
```
mail_location = mbox:~/mail:INBOX=/var/spool/mail/%u
```
Open /etc/dovecot/conf.d/10-ssl.conf and uncomment or change the following lines to enable SSL authentication. Here, I have used certificates created by Postfix. You can use your own certificates or use the one generated by Dovecot:
```
ssl = yes
ssl_cert = < /etc/ssl/certs/ssl-cert-snakeoil.pem
ssl_key =</etc/ssl/private/ssl-cert-snakeoil.key
```
Restart the Dovecot daemon:
```
$ sudo service dovecot restart
```
Test Dovecot by creating a telnet connection. You should see an output similar to the following:
```
$ telnet localhost pop3
```

How it works…

Dovecot is one of the most popular Mail Delivery Agents (MDA) with support for IMAP and POP3 protocols. It works with both major mailbox formats, namely mbox and Maildir. The installation process is simple, and a minimal configuration can get you started with your own IMAP or POP3 service.

Dovecot developers have tried to simplify the configuration by separating it across various small files for each section. All these configuration files are located under /etc/dovecot/conf.d. If you prefer to use a single configuration file, you can replace the default file with the entire working configuration. To get all enabled configurations, use the doveconf -n command:

# mv /etc/dovecot/dovecot.conf /etc/dovecot/dovecot.conf.old
# doveconf -n > /etc/dovecot/dovecot.conf

In this recipe, we have configured Dovecot to support POP3, POP3 secure, IMAP, and IMAP secure. You can choose a single protocol or any combination of them. After setting protocol support, we have set the mailbox type to mbox. If you are using Maildir as your mailbox format, instead replace the mailbox setting with following line:

mail_location = maildir:~/Maildir

Now, when a user wants to check his e-mails, they need to authenticate with the Dovecot server. At this stage, only users with a user account on the server will be able to access their e-mails with Dovecot. To support users without creating a user account, we will need to set up Virtual Users, which is covered in the next recipes.

If you plan to skip SSL setup, you may need to enable plain text authentication under the configuration file, /etc/dovecot/conf.d/10-auth.conf. Find and uncomment the following line and set it to no:

disable_plaintext_auth = yes

The default setting is to allow plain text authentication over SSL connections only. That means the clients that do not support SSL will not be allowed to log in.

How to do it…

Follow these steps to enable IMAP and POP3 with Dovecot:

First, install the Dovecot binaries from the Ubuntu main repository:

$ sudo apt-get update
$ sudo apt-get install dovecot-imapd dovecot-pop3d

You will be prompted for a hostname to be used for certificate generation. Type in a full hostname, for example mail.example.com. You can skip this step if you already have certificates.
Next, proceed with configuring Dovecot. Open the file /etc/dovecot/dovecot.conf:
```
$ sudo nano /etc/dovecot/dovecot.conf
```
Find the Enable installed protocols section and add a new line to set the protocols that you want Dovecot to support:
```
protocols = pop3 pop3s imap imaps
```
Open /etc/dovecot/conf.d/10-mail.conf and set the mailbox to be used. Dovecot supports mbox as well as Maildir. Make sure you set the correct path of your mail directory:
```
mail_location = mbox:~/mail:INBOX=/var/spool/mail/%u
```
Open /etc/dovecot/conf.d/10-ssl.conf and uncomment or change the following lines to enable SSL authentication. Here, I have used certificates created by Postfix. You can use your own certificates or use the one generated by Dovecot:
```
ssl = yes
ssl_cert = < /etc/ssl/certs/ssl-cert-snakeoil.pem
ssl_key =</etc/ssl/private/ssl-cert-snakeoil.key
```
Restart the Dovecot daemon:
```
$ sudo service dovecot restart
```
Test Dovecot by creating a telnet connection. You should see an output similar to the following:
```
$ telnet localhost pop3
```

How it works…

Dovecot is one of the most popular Mail Delivery Agents (MDA) with support for IMAP and POP3 protocols. It works with both major mailbox formats, namely mbox and Maildir. The installation process is simple, and a minimal configuration can get you started with your own IMAP or POP3 service.

Dovecot developers have tried to simplify the configuration by separating it across various small files for each section. All these configuration files are located under /etc/dovecot/conf.d. If you prefer to use a single configuration file, you can replace the default file with the entire working configuration. To get all enabled configurations, use the doveconf -n command:

# mv /etc/dovecot/dovecot.conf /etc/dovecot/dovecot.conf.old
# doveconf -n > /etc/dovecot/dovecot.conf

In this recipe, we have configured Dovecot to support POP3, POP3 secure, IMAP, and IMAP secure. You can choose a single protocol or any combination of them. After setting protocol support, we have set the mailbox type to mbox. If you are using Maildir as your mailbox format, instead replace the mailbox setting with following line:

mail_location = maildir:~/Maildir

Now, when a user wants to check his e-mails, they need to authenticate with the Dovecot server. At this stage, only users with a user account on the server will be able to access their e-mails with Dovecot. To support users without creating a user account, we will need to set up Virtual Users, which is covered in the next recipes.

If you plan to skip SSL setup, you may need to enable plain text authentication under the configuration file, /etc/dovecot/conf.d/10-auth.conf. Find and uncomment the following line and set it to no:

disable_plaintext_auth = yes

The default setting is to allow plain text authentication over SSL connections only. That means the clients that do not support SSL will not be allowed to log in.

How it works…

Dovecot is one of the most popular Mail Delivery Agents (MDA) with support for IMAP and POP3 protocols. It works with both major mailbox formats, namely mbox and Maildir. The installation process is simple, and a minimal configuration can get you started with your own IMAP or POP3 service.

Dovecot developers have tried to simplify the configuration by separating it across various small files for each section. All these configuration files are located under /etc/dovecot/conf.d. If you prefer to use a single configuration file, you can replace the default file with the entire working configuration. To get all enabled configurations, use the doveconf -n command:

# mv /etc/dovecot/dovecot.conf /etc/dovecot/dovecot.conf.old
# doveconf -n > /etc/dovecot/dovecot.conf

In this recipe, we have configured Dovecot to support POP3, POP3 secure, IMAP, and IMAP secure. You can choose a single protocol or any combination of them. After setting protocol support, we have set the mailbox type to mbox. If you are using Maildir as your mailbox format, instead replace the mailbox setting with following line:

mail_location = maildir:~/Maildir

Now, when a user wants to check his e-mails, they need to authenticate with the Dovecot server. At this stage, only users with a user account on the server will be able to access their e-mails with Dovecot. To support users without creating a user account, we will need to set up Virtual Users, which is covered in the next recipes.

If you plan to skip SSL setup, you may need to enable plain text authentication under the configuration file, /etc/dovecot/conf.d/10-auth.conf. Find and uncomment the following line and set it to no:

disable_plaintext_auth = yes

The default setting is to allow plain text authentication over SSL connections only. That means the clients that do not support SSL will not be allowed to log in.

Adding e-mail accounts

In this recipe, we will learn how to add e-mail accounts to Postfix. The easiest way to add a new e-mail account to Postfix is to add a new user account on your server. Postfix will check for user accounts and deliver e-mails to respective users. We will create a virtual user setup so that we do not need to create user accounts for each e-mail user.

Getting ready

You will need access to a root account or an account with sudo privileges.

I assume that you have completed your basic Postfix setup and that it is working properly.

How to do it…

Follow these steps to add e-mail account:

Create a new user account:
```
$ useradd -s /usr/bin/nologin -m vmail
```

Get the UID and GID for this account:

$ grep vmail /etc/passwd
vmail:x:1001:1001::/home/vmail:/usr/bin/nologin

Create a base directory layout for domains and users:

$ sudo mkdir -p /home/vmail/example.org/bob
$ sudo mkdir -p /home/vmail/example.net/alice

Allow only the user vmail to access these files:

$ sudo chown -R vmail:vmail /home/vmail
$ chmod -R 700 /home/vmail

Next, configure Postfix. Edit /etc/postfix/main.cf and add the following lines:

virtual_mailbox_base = /home/vmail
virtual_mailbox_domains = /etc/postfix/virtual_domains
virtual_mailbox_maps = hash:/etc/postfix/virtual_maps
virtual_alias_maps = hash:/etc/postfix/virtual_alias
virtual_uid_maps = static:1001  # user ID for user vmail
virtual_gid_maps = static:1001  # group ID for user vmail

Create the file virtual_domains under /etc/postfix:

$ sudo nano /etc/postfix/virtual_domains

example.org
example.net

Create the virtual_maps file:

$ sudo nano /etc/postfix/virtual_maps
bob@example.org  example.org/bob/
alice@example.org  example.org/alice/
@example.org  example.org/catchall/   # catch all address

Create the virtual_alias file and optionally set a redirect:

$ sudo nano /etc/postfix/virtual_alias
# redirect emails for tim to bob
tim@example.org  bob@example.org

Now generate database of virtual maps and aliases by hashing respective files:

$ sudo postmap /etc/postfix/virtual_maps
$ sudo postmap /etc/postfix/virtual_alias

Reload Postfix and send an e-mail to the newly created address:
```
$ sudo postfix reload
$ sendmail bob@example.org
```

How it works…

Here, we have created a virtual mailbox setup to enable our Postfix server to serve multiple domains as well as add e-mail users without creating user accounts on the server. All e-mails received by virtual users will be stored under the home directory of the vmail user (virtual_mailbox_base in Postfix configuration). When you need to add a new e-mail account, simply add the e-mail address with its respective domain to the virtual_maps file. In case you need to support a new domain, you can easily add it to the virtual_domains file.

The third file we used is virtual_alias. You can set e-mail forwarding in this file. It is handy when you need to create a new alias for an e-mail address or forward e-mails to one or multiple accounts. We have set a catchall entry in the virtual_alias file; this setting will redirect all e-mails received on nonexistent accounts to catchall@example.org, which can be checked by the domain administrator.

There's more…

Using files for virtual users and domains is good for getting started with setup. But once you need to add more and more user accounts and domains it is a good idea to move the users and domains to a database server. This can be easily done by changing the lookup table type. Postfix supports a variety of lookup table types, which include LDAP, MySQL, PGSQL, memcache, SQLite, and many others.

To use MySQL as a backend database, complete the following steps:

Create respective tables for virtual_domain, virtual_maps, and virtual_alias.

Change the Postfix configuration to use MySQL as a lookup table:

virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-domains
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-maps
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias

Add the respective details to each file using the following commands:

$ sudo nano /etc/postfix/mysql-virtual-domains

user = mysql_user
password = mysql_password
hosts = 127.0.0.1
dbname = mysql_db_name
query = SELECT 1 FROM virtual_domains WHERE name='%s'
$ sudo nano /etc/postfix/mysql-virtual-maps

...
query = SELECT 1 FROM virtual_users WHERE email='%s'
$ sudo nano /etc/postfix/mysql-virtual-alias

...
query = SELECT destination FROM virtual_aliases WHERE source='%s'

You can test your mapping with the following command. This should output 1 as a result:
```
$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps
```
Finally, restart the Postfix daemon.

Web console for virtual mailbox administration

The Vimbadmin package provides a web console for virtual mailbox administration. It is a PHP-based open source package. You can get source code and installation instructions at https://github.com/opensolutions/ViMbAdmin.

Getting ready

You will need access to a root account or an account with sudo privileges.

I assume that you have completed your basic Postfix setup and that it is working properly.

How to do it…

Follow these steps to add e-mail account:

Create a new user account:
```
$ useradd -s /usr/bin/nologin -m vmail
```

Get the UID and GID for this account:

$ grep vmail /etc/passwd
vmail:x:1001:1001::/home/vmail:/usr/bin/nologin

Create a base directory layout for domains and users:

$ sudo mkdir -p /home/vmail/example.org/bob
$ sudo mkdir -p /home/vmail/example.net/alice

Allow only the user vmail to access these files:

$ sudo chown -R vmail:vmail /home/vmail
$ chmod -R 700 /home/vmail

Next, configure Postfix. Edit /etc/postfix/main.cf and add the following lines:

virtual_mailbox_base = /home/vmail
virtual_mailbox_domains = /etc/postfix/virtual_domains
virtual_mailbox_maps = hash:/etc/postfix/virtual_maps
virtual_alias_maps = hash:/etc/postfix/virtual_alias
virtual_uid_maps = static:1001  # user ID for user vmail
virtual_gid_maps = static:1001  # group ID for user vmail

Create the file virtual_domains under /etc/postfix:

$ sudo nano /etc/postfix/virtual_domains

example.org
example.net

Create the virtual_maps file:

$ sudo nano /etc/postfix/virtual_maps
bob@example.org  example.org/bob/
alice@example.org  example.org/alice/
@example.org  example.org/catchall/   # catch all address

Create the virtual_alias file and optionally set a redirect:

$ sudo nano /etc/postfix/virtual_alias
# redirect emails for tim to bob
tim@example.org  bob@example.org

Now generate database of virtual maps and aliases by hashing respective files:

$ sudo postmap /etc/postfix/virtual_maps
$ sudo postmap /etc/postfix/virtual_alias

Reload Postfix and send an e-mail to the newly created address:
```
$ sudo postfix reload
$ sendmail bob@example.org
```

How it works…

Here, we have created a virtual mailbox setup to enable our Postfix server to serve multiple domains as well as add e-mail users without creating user accounts on the server. All e-mails received by virtual users will be stored under the home directory of the vmail user (virtual_mailbox_base in Postfix configuration). When you need to add a new e-mail account, simply add the e-mail address with its respective domain to the virtual_maps file. In case you need to support a new domain, you can easily add it to the virtual_domains file.

The third file we used is virtual_alias. You can set e-mail forwarding in this file. It is handy when you need to create a new alias for an e-mail address or forward e-mails to one or multiple accounts. We have set a catchall entry in the virtual_alias file; this setting will redirect all e-mails received on nonexistent accounts to catchall@example.org, which can be checked by the domain administrator.

There's more…

Using files for virtual users and domains is good for getting started with setup. But once you need to add more and more user accounts and domains it is a good idea to move the users and domains to a database server. This can be easily done by changing the lookup table type. Postfix supports a variety of lookup table types, which include LDAP, MySQL, PGSQL, memcache, SQLite, and many others.

To use MySQL as a backend database, complete the following steps:

Create respective tables for virtual_domain, virtual_maps, and virtual_alias.

Change the Postfix configuration to use MySQL as a lookup table:

virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-domains
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-maps
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias

Add the respective details to each file using the following commands:

$ sudo nano /etc/postfix/mysql-virtual-domains

user = mysql_user
password = mysql_password
hosts = 127.0.0.1
dbname = mysql_db_name
query = SELECT 1 FROM virtual_domains WHERE name='%s'
$ sudo nano /etc/postfix/mysql-virtual-maps

...
query = SELECT 1 FROM virtual_users WHERE email='%s'
$ sudo nano /etc/postfix/mysql-virtual-alias

...
query = SELECT destination FROM virtual_aliases WHERE source='%s'

You can test your mapping with the following command. This should output 1 as a result:
```
$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps
```
Finally, restart the Postfix daemon.

Web console for virtual mailbox administration

The Vimbadmin package provides a web console for virtual mailbox administration. It is a PHP-based open source package. You can get source code and installation instructions at https://github.com/opensolutions/ViMbAdmin.

How to do it…

Follow these steps to add e-mail account:

Create a new user account:
```
$ useradd -s /usr/bin/nologin -m vmail
```

Get the UID and GID for this account:

$ grep vmail /etc/passwd
vmail:x:1001:1001::/home/vmail:/usr/bin/nologin

Create a base directory layout for domains and users:

$ sudo mkdir -p /home/vmail/example.org/bob
$ sudo mkdir -p /home/vmail/example.net/alice

Allow only the user vmail to access these files:

$ sudo chown -R vmail:vmail /home/vmail
$ chmod -R 700 /home/vmail

Next, configure Postfix. Edit /etc/postfix/main.cf and add the following lines:

virtual_mailbox_base = /home/vmail
virtual_mailbox_domains = /etc/postfix/virtual_domains
virtual_mailbox_maps = hash:/etc/postfix/virtual_maps
virtual_alias_maps = hash:/etc/postfix/virtual_alias
virtual_uid_maps = static:1001  # user ID for user vmail
virtual_gid_maps = static:1001  # group ID for user vmail

Create the file virtual_domains under /etc/postfix:

$ sudo nano /etc/postfix/virtual_domains

example.org
example.net

Create the virtual_maps file:

$ sudo nano /etc/postfix/virtual_maps
bob@example.org  example.org/bob/
alice@example.org  example.org/alice/
@example.org  example.org/catchall/   # catch all address

Create the virtual_alias file and optionally set a redirect:

$ sudo nano /etc/postfix/virtual_alias
# redirect emails for tim to bob
tim@example.org  bob@example.org

Now generate database of virtual maps and aliases by hashing respective files:

$ sudo postmap /etc/postfix/virtual_maps
$ sudo postmap /etc/postfix/virtual_alias

Reload Postfix and send an e-mail to the newly created address:
```
$ sudo postfix reload
$ sendmail bob@example.org
```

How it works…

Here, we have created a virtual mailbox setup to enable our Postfix server to serve multiple domains as well as add e-mail users without creating user accounts on the server. All e-mails received by virtual users will be stored under the home directory of the vmail user (virtual_mailbox_base in Postfix configuration). When you need to add a new e-mail account, simply add the e-mail address with its respective domain to the virtual_maps file. In case you need to support a new domain, you can easily add it to the virtual_domains file.

The third file we used is virtual_alias. You can set e-mail forwarding in this file. It is handy when you need to create a new alias for an e-mail address or forward e-mails to one or multiple accounts. We have set a catchall entry in the virtual_alias file; this setting will redirect all e-mails received on nonexistent accounts to catchall@example.org, which can be checked by the domain administrator.

There's more…

Using files for virtual users and domains is good for getting started with setup. But once you need to add more and more user accounts and domains it is a good idea to move the users and domains to a database server. This can be easily done by changing the lookup table type. Postfix supports a variety of lookup table types, which include LDAP, MySQL, PGSQL, memcache, SQLite, and many others.

To use MySQL as a backend database, complete the following steps:

Create respective tables for virtual_domain, virtual_maps, and virtual_alias.

Change the Postfix configuration to use MySQL as a lookup table:

virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-domains
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-maps
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias

Add the respective details to each file using the following commands:

$ sudo nano /etc/postfix/mysql-virtual-domains

user = mysql_user
password = mysql_password
hosts = 127.0.0.1
dbname = mysql_db_name
query = SELECT 1 FROM virtual_domains WHERE name='%s'
$ sudo nano /etc/postfix/mysql-virtual-maps

...
query = SELECT 1 FROM virtual_users WHERE email='%s'
$ sudo nano /etc/postfix/mysql-virtual-alias

...
query = SELECT destination FROM virtual_aliases WHERE source='%s'

You can test your mapping with the following command. This should output 1 as a result:
```
$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps
```
Finally, restart the Postfix daemon.

Web console for virtual mailbox administration

The Vimbadmin package provides a web console for virtual mailbox administration. It is a PHP-based open source package. You can get source code and installation instructions at https://github.com/opensolutions/ViMbAdmin.

How it works…

Here, we have created a virtual mailbox setup to enable our Postfix server to serve multiple domains as well as add e-mail users without creating user accounts on the server. All e-mails received by virtual users will be stored under the home directory of the vmail user (virtual_mailbox_base in Postfix configuration). When you need to add a new e-mail account, simply add the e-mail address with its respective domain to the virtual_maps file. In case you need to support a new domain, you can easily add it to the virtual_domains file.

The third file we used is virtual_alias. You can set e-mail forwarding in this file. It is handy when you need to create a new alias for an e-mail address or forward e-mails to one or multiple accounts. We have set a catchall entry in the virtual_alias file; this setting will redirect all e-mails received on nonexistent accounts to catchall@example.org, which can be checked by the domain administrator.

There's more…

Using files for virtual users and domains is good for getting started with setup. But once you need to add more and more user accounts and domains it is a good idea to move the users and domains to a database server. This can be easily done by changing the lookup table type. Postfix supports a variety of lookup table types, which include LDAP, MySQL, PGSQL, memcache, SQLite, and many others.

To use MySQL as a backend database, complete the following steps:

Create respective tables for virtual_domain, virtual_maps, and virtual_alias.

Change the Postfix configuration to use MySQL as a lookup table:

virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-domains
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-maps
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias

Add the respective details to each file using the following commands:

$ sudo nano /etc/postfix/mysql-virtual-domains

user = mysql_user
password = mysql_password
hosts = 127.0.0.1
dbname = mysql_db_name
query = SELECT 1 FROM virtual_domains WHERE name='%s'
$ sudo nano /etc/postfix/mysql-virtual-maps

...
query = SELECT 1 FROM virtual_users WHERE email='%s'
$ sudo nano /etc/postfix/mysql-virtual-alias

...
query = SELECT destination FROM virtual_aliases WHERE source='%s'

You can test your mapping with the following command. This should output 1 as a result:
```
$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps
```
Finally, restart the Postfix daemon.

Web console for virtual mailbox administration

The Vimbadmin package provides a web console for virtual mailbox administration. It is a PHP-based open source package. You can get source code and installation instructions at https://github.com/opensolutions/ViMbAdmin.

There's more…

Using files for virtual users and domains is good for getting started with setup. But once you need to add more and more user accounts and domains it is a good idea to move the users and domains to a database server. This can be easily done by changing the lookup table type. Postfix supports a variety of lookup table types, which include LDAP, MySQL, PGSQL, memcache, SQLite, and many others.

To use MySQL as a backend database, complete the following steps:

Create respective tables for virtual_domain, virtual_maps, and virtual_alias.

Change the Postfix configuration to use MySQL as a lookup table:

virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-domains
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-maps
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias

Add the respective details to each file using the following commands:

$ sudo nano /etc/postfix/mysql-virtual-domains

user = mysql_user
password = mysql_password
hosts = 127.0.0.1
dbname = mysql_db_name
query = SELECT 1 FROM virtual_domains WHERE name='%s'
$ sudo nano /etc/postfix/mysql-virtual-maps

...
query = SELECT 1 FROM virtual_users WHERE email='%s'
$ sudo nano /etc/postfix/mysql-virtual-alias

...
query = SELECT destination FROM virtual_aliases WHERE source='%s'

You can test your mapping with the following command. This should output 1 as a result:
```
$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps
```
Finally, restart the Postfix daemon.

Web console for virtual mailbox administration

The Vimbadmin package provides a web console for virtual mailbox administration. It is a PHP-based open source package. You can get source code and installation instructions at https://github.com/opensolutions/ViMbAdmin.

Web console for virtual mailbox administration

The Vimbadmin package provides a web console for virtual mailbox administration. It is a PHP-based open source package. You can get source code and installation instructions at https://github.com/opensolutions/ViMbAdmin.

Mail filtering with spam-assassin

In this recipe, we will learn how to install and set up a well-known e-mail filtering program, spam-assassin.

Getting ready

You will need access to a root account or an account with sudo privileges.

You need to have Postfix installed and working.

How to do it…

Follow these steps to filter mail with spam-assassin:

Install spam-assassin with the following command:

$ sudo apt-get update
$ sudo apt-get install spamassassin spamc

Create a user account and group for spam-assassin:

$ sudo groupadd spamd
$ sudo useradd -g spamd -s /usr/bin/nologin \
-d /var/log/spamassassin -m spamd

Change the default settings for the spam daemon. Open /etc/default/spamassassin and update the following lines:

ENABLED=1
SAHOME="/var/log/spamassassin/"
OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir ${SAHOME} -s ${SAHOME}spamd.log"
PIDFILE="${SAHOME}spamd.pid"
CRON=1

Optionally, configure spam rules by changing values in /etc/spamassassin/local.cf:

trusted_networks 10.0.2.  # set your trusted network
required_score 3.0    # 3 + will be marked as spam

Next, we need to change the Postfix settings to pass e-mails through spam-assassin. Open /etc/postfix/master.cf and find the following line:
```
smtp      inet  n       -       -       -       -       smtpd
```
Add the content filtering option:
```
-o content_filter=spamassassin
```

Define the content filter block by adding the following lines to the end of the file:

spamassassin unix -     n       n       -       -       pipe
        user=spamd argv=/usr/bin/spamc -f -e
        /usr/sbin/sendmail -oi -f ${sender} ${recipient}

Finally, restart spam-assassin and Postfix:

$ sudo service spamassassin start
$ sudo service postfix reload

You can check spam-assassin and mail logs to verify that spam-assassin is working properly:
```
$ less /var/log/spamassassin/spamd.log
$ less /var/log/mail.log
```

How it works…

Spam filtering works with the help of a piping mechanism provided by Postfix. We have created a new Unix pipe which will be used to filter e-mails. Postfix will pass all e-mails through this pipe, which will be then scanned through spam-assassin to determine the spam score. If given e-mail scores below the configured threshold, then it passes the filter without any modification; otherwise, spam-assassin adds a spam header to the e-mail.

Spam-assassin works with a Bayesian classifier to classify e-mails as spam or not spam. Basically, it checks the content of the e-mail and determines the score based on content.

There's more…

You can train spam-assassin's Bayesian classifier to get more accurate spam detections.

The following command will train spam-assassin with spam contents (--spam):

$ sudo sa-learn --spam -u spamd --dir ~/Maildir/.Junk/* -D

To train with non-spam content, use the following command (--ham):

$ sudo sa-learn --ham -u spamd --dir ~/Maildir/.INBOX/* -D

If you are using the mbox format, replace --dir ~/Maildir/.Junk/* with the option --mbox.

Getting ready

You will need access to a root account or an account with sudo privileges.

You need to have Postfix installed and working.

How to do it…

Follow these steps to filter mail with spam-assassin:

Install spam-assassin with the following command:

$ sudo apt-get update
$ sudo apt-get install spamassassin spamc

Create a user account and group for spam-assassin:

$ sudo groupadd spamd
$ sudo useradd -g spamd -s /usr/bin/nologin \
-d /var/log/spamassassin -m spamd

Change the default settings for the spam daemon. Open /etc/default/spamassassin and update the following lines:

ENABLED=1
SAHOME="/var/log/spamassassin/"
OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir ${SAHOME} -s ${SAHOME}spamd.log"
PIDFILE="${SAHOME}spamd.pid"
CRON=1

Optionally, configure spam rules by changing values in /etc/spamassassin/local.cf:

trusted_networks 10.0.2.  # set your trusted network
required_score 3.0    # 3 + will be marked as spam

Next, we need to change the Postfix settings to pass e-mails through spam-assassin. Open /etc/postfix/master.cf and find the following line:
```
smtp      inet  n       -       -       -       -       smtpd
```
Add the content filtering option:
```
-o content_filter=spamassassin
```

Define the content filter block by adding the following lines to the end of the file:

spamassassin unix -     n       n       -       -       pipe
        user=spamd argv=/usr/bin/spamc -f -e
        /usr/sbin/sendmail -oi -f ${sender} ${recipient}

Finally, restart spam-assassin and Postfix:

$ sudo service spamassassin start
$ sudo service postfix reload

You can check spam-assassin and mail logs to verify that spam-assassin is working properly:
```
$ less /var/log/spamassassin/spamd.log
$ less /var/log/mail.log
```

How it works…

Spam filtering works with the help of a piping mechanism provided by Postfix. We have created a new Unix pipe which will be used to filter e-mails. Postfix will pass all e-mails through this pipe, which will be then scanned through spam-assassin to determine the spam score. If given e-mail scores below the configured threshold, then it passes the filter without any modification; otherwise, spam-assassin adds a spam header to the e-mail.

Spam-assassin works with a Bayesian classifier to classify e-mails as spam or not spam. Basically, it checks the content of the e-mail and determines the score based on content.

There's more…

You can train spam-assassin's Bayesian classifier to get more accurate spam detections.

The following command will train spam-assassin with spam contents (--spam):

$ sudo sa-learn --spam -u spamd --dir ~/Maildir/.Junk/* -D

To train with non-spam content, use the following command (--ham):

$ sudo sa-learn --ham -u spamd --dir ~/Maildir/.INBOX/* -D

If you are using the mbox format, replace --dir ~/Maildir/.Junk/* with the option --mbox.

How to do it…

Follow these steps to filter mail with spam-assassin:

Install spam-assassin with the following command:

$ sudo apt-get update
$ sudo apt-get install spamassassin spamc

Create a user account and group for spam-assassin:

$ sudo groupadd spamd
$ sudo useradd -g spamd -s /usr/bin/nologin \
-d /var/log/spamassassin -m spamd

Change the default settings for the spam daemon. Open /etc/default/spamassassin and update the following lines:

ENABLED=1
SAHOME="/var/log/spamassassin/"
OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir ${SAHOME} -s ${SAHOME}spamd.log"
PIDFILE="${SAHOME}spamd.pid"
CRON=1

Optionally, configure spam rules by changing values in /etc/spamassassin/local.cf:

trusted_networks 10.0.2.  # set your trusted network
required_score 3.0    # 3 + will be marked as spam

Next, we need to change the Postfix settings to pass e-mails through spam-assassin. Open /etc/postfix/master.cf and find the following line:
```
smtp      inet  n       -       -       -       -       smtpd
```
Add the content filtering option:
```
-o content_filter=spamassassin
```

Define the content filter block by adding the following lines to the end of the file:

spamassassin unix -     n       n       -       -       pipe
        user=spamd argv=/usr/bin/spamc -f -e
        /usr/sbin/sendmail -oi -f ${sender} ${recipient}

Finally, restart spam-assassin and Postfix:

$ sudo service spamassassin start
$ sudo service postfix reload

You can check spam-assassin and mail logs to verify that spam-assassin is working properly:
```
$ less /var/log/spamassassin/spamd.log
$ less /var/log/mail.log
```

How it works…

Spam filtering works with the help of a piping mechanism provided by Postfix. We have created a new Unix pipe which will be used to filter e-mails. Postfix will pass all e-mails through this pipe, which will be then scanned through spam-assassin to determine the spam score. If given e-mail scores below the configured threshold, then it passes the filter without any modification; otherwise, spam-assassin adds a spam header to the e-mail.

Spam-assassin works with a Bayesian classifier to classify e-mails as spam or not spam. Basically, it checks the content of the e-mail and determines the score based on content.

There's more…

You can train spam-assassin's Bayesian classifier to get more accurate spam detections.

The following command will train spam-assassin with spam contents (--spam):

$ sudo sa-learn --spam -u spamd --dir ~/Maildir/.Junk/* -D

To train with non-spam content, use the following command (--ham):

$ sudo sa-learn --ham -u spamd --dir ~/Maildir/.INBOX/* -D

If you are using the mbox format, replace --dir ~/Maildir/.Junk/* with the option --mbox.

How it works…

Spam filtering works with the help of a piping mechanism provided by Postfix. We have created a new Unix pipe which will be used to filter e-mails. Postfix will pass all e-mails through this pipe, which will be then scanned through spam-assassin to determine the spam score. If given e-mail scores below the configured threshold, then it passes the filter without any modification; otherwise, spam-assassin adds a spam header to the e-mail.

Spam-assassin works with a Bayesian classifier to classify e-mails as spam or not spam. Basically, it checks the content of the e-mail and determines the score based on content.

There's more…

You can train spam-assassin's Bayesian classifier to get more accurate spam detections.

The following command will train spam-assassin with spam contents (--spam):

$ sudo sa-learn --spam -u spamd --dir ~/Maildir/.Junk/* -D

To train with non-spam content, use the following command (--ham):

$ sudo sa-learn --ham -u spamd --dir ~/Maildir/.INBOX/* -D

If you are using the mbox format, replace --dir ~/Maildir/.Junk/* with the option --mbox.

There's more…

You can train spam-assassin's Bayesian classifier to get more accurate spam detections.

The following command will train spam-assassin with spam contents (--spam):

$ sudo sa-learn --spam -u spamd --dir ~/Maildir/.Junk/* -D

To train with non-spam content, use the following command (--ham):

$ sudo sa-learn --ham -u spamd --dir ~/Maildir/.INBOX/* -D

If you are using the mbox format, replace --dir ~/Maildir/.Junk/* with the option --mbox.

Troubleshooting the mail server

Sometimes you may face problems such as e-mails not being sent, delayed delivery or mail bouncing, issues while fetching e-mails, and login failures. In this recipe, we will learn how to identify the exact problem behind these issues. We will learn how to use debugging tools and read the logs of Postfix and Dovecot.

Getting ready

You will need access to a root account or an account with sudo privileges.

It is assumed that you have already installed Postfix and Dovecot servers.

How to do it…

Follow these steps to troubleshoot the mail server:

Start with checking the status of Postfix and Dovecot. If you get output that says stop/waiting or not running then the respective service is not running:
```
$ sudo service postfix status
$ sudo service dovecot status
```
Try to restart the respective services. Restarting may give you error messages. Also check for startup logs under /var/log/mail.log:
```
$ sudo service postfix restart
$ less /var/log/mail.log
```
You can use a tail command to monitor the stream of logs while the service is running. You can easily filter the output of tail by piping it to a grep command:
```
$ tail -f /var/log/mail.log
```
Use grep to only view selected logs:
```
$ tail -f /var/log/mail.log | grep "dovecot"
```

Use grep -v to filter/remove selected logs:

$ tail -f /var/log/mail.log | grep -v "dovecot"

You can check other log files such as /var/log/mail.err and /var/log/upstart/dovecot.log.
You may want to enable verbose logging to get detailed debugging information. To enable debug mode on Dovecot, edit 10-logging.conf and enable auth_verbose and mail_debug variables:
```
$ sudo nano /etc/dovecot/conf.d/10-logging.conf
```
```
auth_verbose = yes
mail_debug = yes
```
Restart Dovecot:
```
$ sudo service dovecot restart
```

To enable verbose logging on Postfix, edit master.cf file and add the -v argument:

$ sudo nano /etc/postfix/master.cf
smtp      inet  n       -       -       -       -       smtpd -v

Restart Postfix.

Turn off chroot operations:

$ sudo nano /etc/postfix/master.cf
smtp      inet  n       -       n       -       -       smtpd

Check user account with Dovecot:

$ doveadm username useremail@example.com

If you have set virtual users, check if they are working properly:

$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps

Check respective ports used by Postfix and Dovecot. Postfix uses ports 25, 465, 587 and Dovecot uses port 993 and 995:
```
$ telnet localhost 993
```
Check netstat to make sure services are listening:
```
$ sudo netstat -plutn
```
Check for DNS resolution and MX records:
```
$ host -t mx example.com
```
Check if spam filters and antivirus scanners are working properly.

Getting ready

You will need access to a root account or an account with sudo privileges.

It is assumed that you have already installed Postfix and Dovecot servers.

How to do it…

Follow these steps to troubleshoot the mail server:

Start with checking the status of Postfix and Dovecot. If you get output that says stop/waiting or not running then the respective service is not running:
```
$ sudo service postfix status
$ sudo service dovecot status
```
Try to restart the respective services. Restarting may give you error messages. Also check for startup logs under /var/log/mail.log:
```
$ sudo service postfix restart
$ less /var/log/mail.log
```
You can use a tail command to monitor the stream of logs while the service is running. You can easily filter the output of tail by piping it to a grep command:
```
$ tail -f /var/log/mail.log
```
Use grep to only view selected logs:
```
$ tail -f /var/log/mail.log | grep "dovecot"
```

Use grep -v to filter/remove selected logs:

$ tail -f /var/log/mail.log | grep -v "dovecot"

You can check other log files such as /var/log/mail.err and /var/log/upstart/dovecot.log.
You may want to enable verbose logging to get detailed debugging information. To enable debug mode on Dovecot, edit 10-logging.conf and enable auth_verbose and mail_debug variables:
```
$ sudo nano /etc/dovecot/conf.d/10-logging.conf
```
```
auth_verbose = yes
mail_debug = yes
```
Restart Dovecot:
```
$ sudo service dovecot restart
```

To enable verbose logging on Postfix, edit master.cf file and add the -v argument:

$ sudo nano /etc/postfix/master.cf
smtp      inet  n       -       -       -       -       smtpd -v

Restart Postfix.

Turn off chroot operations:

$ sudo nano /etc/postfix/master.cf
smtp      inet  n       -       n       -       -       smtpd

Check user account with Dovecot:

$ doveadm username useremail@example.com

If you have set virtual users, check if they are working properly:

$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps

Check respective ports used by Postfix and Dovecot. Postfix uses ports 25, 465, 587 and Dovecot uses port 993 and 995:
```
$ telnet localhost 993
```
Check netstat to make sure services are listening:
```
$ sudo netstat -plutn
```
Check for DNS resolution and MX records:
```
$ host -t mx example.com
```
Check if spam filters and antivirus scanners are working properly.

How to do it…

Follow these steps to troubleshoot the mail server:

Start with checking the status of Postfix and Dovecot. If you get output that says stop/waiting or not running then the respective service is not running:
```
$ sudo service postfix status
$ sudo service dovecot status
```
Try to restart the respective services. Restarting may give you error messages. Also check for startup logs under /var/log/mail.log:
```
$ sudo service postfix restart
$ less /var/log/mail.log
```
You can use a tail command to monitor the stream of logs while the service is running. You can easily filter the output of tail by piping it to a grep command:
```
$ tail -f /var/log/mail.log
```
Use grep to only view selected logs:
```
$ tail -f /var/log/mail.log | grep "dovecot"
```

Use grep -v to filter/remove selected logs:

$ tail -f /var/log/mail.log | grep -v "dovecot"

You can check other log files such as /var/log/mail.err and /var/log/upstart/dovecot.log.
You may want to enable verbose logging to get detailed debugging information. To enable debug mode on Dovecot, edit 10-logging.conf and enable auth_verbose and mail_debug variables:
```
$ sudo nano /etc/dovecot/conf.d/10-logging.conf
```
```
auth_verbose = yes
mail_debug = yes
```
Restart Dovecot:
```
$ sudo service dovecot restart
```

To enable verbose logging on Postfix, edit master.cf file and add the -v argument:

$ sudo nano /etc/postfix/master.cf
smtp      inet  n       -       -       -       -       smtpd -v

Restart Postfix.

Turn off chroot operations:

$ sudo nano /etc/postfix/master.cf
smtp      inet  n       -       n       -       -       smtpd

Check user account with Dovecot:

$ doveadm username useremail@example.com

If you have set virtual users, check if they are working properly:

$ postmap -q bob@example.org mysql:/etc/postfix/mysql-virtual-maps

Check respective ports used by Postfix and Dovecot. Postfix uses ports 25, 465, 587 and Dovecot uses port 993 and 995:
```
$ telnet localhost 993
```
Check netstat to make sure services are listening:
```
$ sudo netstat -plutn
```
Check for DNS resolution and MX records:
```
$ host -t mx example.com
```
Check if spam filters and antivirus scanners are working properly.

Installing the Zimbra mail server

Until now, we have installed Postfix, Dovecot, spam-assassin, and other tools separately. In this recipe, we will learn how to install the Zimbra collaboration server, which covers all tools in a single package. The Zimbra server contains Postfix, MySQL, OpenLDAP, ClamAV, and Spam-Assassin, Calendar, and various other features. Zimbra provides a paid option as well as an open source version. We will be installing an open source version of the Zimbra server in single server mode.

Getting ready

As always, you will need access to a root account or an account with sudo privileges.

For Zimbra to work properly, you will need the following minimum configuration for your server:

At least 1.5 GHz of CPU 2 GHz recommended
Minimum 8 GB of memory
Minimum 10 GB of storage 20 GB recommended

You will need to set proper DNS and MX records for your domain.

You will also need various ports, as follows:

Postfix/LMTP 25, 7025
HTTP 80, 443
POP3 110, 995
IMAP 143, 993
LDAP 389

How to do it…

Follow these steps to install Zimbra collaboration server:

Install the dependency packages before starting with the Zimbra installation:

$ sudo apt-get update
$ sudo apt-get install libperl5.18 libaio1 unzip pax sysstat sqlite3 libgmp10

Download and extract the Zimbra open source package using the following command:

$ wget https://files.zimbra.com/downloads/8.6.0_GA/zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116.tgz
$ tar -zxvf zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116.tgz
$ cd zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116

Make sure you have set the proper hostname and hosts entries in respective files:

$ cat /etc/hosts
127.0.0.1 localhost
119.9.107.28    mail.server.local     mail
$ cat /etc/hostname
mail.server.local

Start the Zimbra installation by executing the installer:
```
$ sudo ./install.sh
```
The installation process will ask you to agree with License Agreement. Type y and press Enter to continue:
On acceptance of agreement, Zimbra will check for dependencies and then ask for the component selection. I have chosen to skip a few components. Type y when asked for confirmation:
Type y when asked for package selection confirmation.
The installation process will take some time. As installation completes, the Zimbra configuration menu will be displayed. Here, you need to set an admin account password:
On the main menu, select 6 to choose zimbra-store and then type 4 for the admin password. The new prompt will ask for the admin account password:
Then, type r to come back to the main menu and then type a to apply settings, and again press Enter to save settings:
Finally, apply all configurations when asked. Zimbra will ask you to send installation notification to Zimbra. Choose Yes by typing y to notify Zimbra:
Now you can access your Zimbra server with the domain name of your server or IP address. Your browser may prompt for a non-trusted server certificate, as shown in the following screenshot:
You can access the Inbox panel on port 7071, https://yourserver.tld:7071.

How it works…

Zimbra combines various commonly used packages in a single package and provides a web interface to work with them. It reduces the efforts required in installing and configuring all tools separately. For any additional features, you can always switch to the Zimbra collaboration server, Network Edition.

There's more…

If you are planning to use Zimbra on your local network, you will need a DNS server set up. Alternatively, you can use the tool dnsmasq. It is a small package that sets up a quick DNS environment on your local network.

Getting ready

As always, you will need access to a root account or an account with sudo privileges.

For Zimbra to work properly, you will need the following minimum configuration for your server:

At least 1.5 GHz of CPU 2 GHz recommended
Minimum 8 GB of memory
Minimum 10 GB of storage 20 GB recommended

You will need to set proper DNS and MX records for your domain.

You will also need various ports, as follows:

Postfix/LMTP 25, 7025
HTTP 80, 443
POP3 110, 995
IMAP 143, 993
LDAP 389

How to do it…

Follow these steps to install Zimbra collaboration server:

Install the dependency packages before starting with the Zimbra installation:

$ sudo apt-get update
$ sudo apt-get install libperl5.18 libaio1 unzip pax sysstat sqlite3 libgmp10

Download and extract the Zimbra open source package using the following command:

$ wget https://files.zimbra.com/downloads/8.6.0_GA/zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116.tgz
$ tar -zxvf zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116.tgz
$ cd zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116

Make sure you have set the proper hostname and hosts entries in respective files:

$ cat /etc/hosts
127.0.0.1 localhost
119.9.107.28    mail.server.local     mail
$ cat /etc/hostname
mail.server.local

Start the Zimbra installation by executing the installer:
```
$ sudo ./install.sh
```
The installation process will ask you to agree with License Agreement. Type y and press Enter to continue:
On acceptance of agreement, Zimbra will check for dependencies and then ask for the component selection. I have chosen to skip a few components. Type y when asked for confirmation:
Type y when asked for package selection confirmation.
The installation process will take some time. As installation completes, the Zimbra configuration menu will be displayed. Here, you need to set an admin account password:
On the main menu, select 6 to choose zimbra-store and then type 4 for the admin password. The new prompt will ask for the admin account password:
Then, type r to come back to the main menu and then type a to apply settings, and again press Enter to save settings:
Finally, apply all configurations when asked. Zimbra will ask you to send installation notification to Zimbra. Choose Yes by typing y to notify Zimbra:
Now you can access your Zimbra server with the domain name of your server or IP address. Your browser may prompt for a non-trusted server certificate, as shown in the following screenshot:
You can access the Inbox panel on port 7071, https://yourserver.tld:7071.

How it works…

Zimbra combines various commonly used packages in a single package and provides a web interface to work with them. It reduces the efforts required in installing and configuring all tools separately. For any additional features, you can always switch to the Zimbra collaboration server, Network Edition.

There's more…

If you are planning to use Zimbra on your local network, you will need a DNS server set up. Alternatively, you can use the tool dnsmasq. It is a small package that sets up a quick DNS environment on your local network.

How to do it…

Follow these steps to install Zimbra collaboration server:

Install the dependency packages before starting with the Zimbra installation:

$ sudo apt-get update
$ sudo apt-get install libperl5.18 libaio1 unzip pax sysstat sqlite3 libgmp10

Download and extract the Zimbra open source package using the following command:

$ wget https://files.zimbra.com/downloads/8.6.0_GA/zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116.tgz
$ tar -zxvf zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116.tgz
$ cd zcs-8.6.0_GA_1153.UBUNTU14_64.20141215151116

Make sure you have set the proper hostname and hosts entries in respective files:

$ cat /etc/hosts
127.0.0.1 localhost
119.9.107.28    mail.server.local     mail
$ cat /etc/hostname
mail.server.local

Start the Zimbra installation by executing the installer:
```
$ sudo ./install.sh
```
The installation process will ask you to agree with License Agreement. Type y and press Enter to continue:
On acceptance of agreement, Zimbra will check for dependencies and then ask for the component selection. I have chosen to skip a few components. Type y when asked for confirmation:
Type y when asked for package selection confirmation.
The installation process will take some time. As installation completes, the Zimbra configuration menu will be displayed. Here, you need to set an admin account password:
On the main menu, select 6 to choose zimbra-store and then type 4 for the admin password. The new prompt will ask for the admin account password:
Then, type r to come back to the main menu and then type a to apply settings, and again press Enter to save settings:
Finally, apply all configurations when asked. Zimbra will ask you to send installation notification to Zimbra. Choose Yes by typing y to notify Zimbra:
Now you can access your Zimbra server with the domain name of your server or IP address. Your browser may prompt for a non-trusted server certificate, as shown in the following screenshot:
You can access the Inbox panel on port 7071, https://yourserver.tld:7071.

How it works…

Zimbra combines various commonly used packages in a single package and provides a web interface to work with them. It reduces the efforts required in installing and configuring all tools separately. For any additional features, you can always switch to the Zimbra collaboration server, Network Edition.

There's more…

If you are planning to use Zimbra on your local network, you will need a DNS server set up. Alternatively, you can use the tool dnsmasq. It is a small package that sets up a quick DNS environment on your local network.

How it works…

Zimbra combines various commonly used packages in a single package and provides a web interface to work with them. It reduces the efforts required in installing and configuring all tools separately. For any additional features, you can always switch to the Zimbra collaboration server, Network Edition.

There's more…

If you are planning to use Zimbra on your local network, you will need a DNS server set up. Alternatively, you can use the tool dnsmasq. It is a small package that sets up a quick DNS environment on your local network.

There's more…

If you are planning to use Zimbra on your local network, you will need a DNS server set up. Alternatively, you can use the tool dnsmasq. It is a small package that sets up a quick DNS environment on your local network.

You're reading from Linux: Powerful Server Administration Recipes for CentOS 7, RHEL 7, and Ubuntu Server Administration

Table of Contents (6) Chapters

Chapter 4. Working with Mail Servers

Introduction

Sending e-mails with Postfix

Getting ready

How to do it…

How it works…

Tip

See also

Getting ready

How to do it…

How it works…

Tip

See also

How to do it…

How it works…

Tip

See also

How it works…

Tip

See also

See also

Enabling IMAP and POP3 with Dovecot

Getting ready

How to do it…

How it works…

See also

Getting ready

How to do it…

How it works…

See also

How to do it…

How it works…

See also

How it works…

See also

See also

Adding e-mail accounts

Getting ready

How to do it…

How it works…

There's more…

Web console for virtual mailbox administration

See also

Getting ready

How to do it…

How it works…

There's more…

Web console for virtual mailbox administration

See also

How to do it…

How it works…

There's more…

Web console for virtual mailbox administration

See also

How it works…

There's more…

Web console for virtual mailbox administration

See also

There's more…

Web console for virtual mailbox administration

See also

Web console for virtual mailbox administration

See also

Mail filtering with spam-assassin

Getting ready

How to do it…

How it works…

There's more…

See also

Getting ready

How to do it…

How it works…

There's more…

See also

How to do it…

How it works…

There's more…

See also