Mail queues
E-mails in JIRA are not sent immediately when an operation is performed. Instead, they are placed in a mail queue, which JIRA empties periodically (every minute). This is very similar to the real-life scenario, where e-mails are placed in post boxes and picked up everyday.
Viewing the mail queue
Normally, you do not need to manage the mail queue. JIRA automatically places e-mails into the queue and flushes them periodically. However, as an administrator, there may be times when you wish to inspect the current queue and check if there are e-mails that are "stuck" and cannot be sent. E-mails can be stuck for a number of reasons. For example, if configured, SMTP mail server is not accessible. JIRA will automatically re-try.
Perform the following steps to view the mail queue and the mails it contains:
Browse to the Mail section.
Click on the Mail Queue tab to bring up the Mail Queue page:
This page provides you with a one-page view of the current e-mails in the queue waiting to be delivered...