Writing a simple SMTP server

In this recipe, we will learn how to build an SMTP server and a client, as a simple mail server and a client. We will use Python's smtpd library for this recipe. You may read more about smtpd at https://docs.python.org/3/library/smtpd.html.

Getting ready

First, we will write an SMTP server that listens on a particular host and a particular port. Then we will write an SMTP client that connects to the same host and port, with the fromaddress, toaddress, subject, and message passed as the other arguments.

How to do it...

The server receives...