Update email documentation to highlight that OutOfMemoryError can stop email processing

A common explanation for customers reporting that their JIRA instance is not sending emails, or is not creating issues and comments from email, is that they have experienced OutOfMemoryErrors. There is a high correlation between that problem report and OutOfMemoryError in the logs.

The fix is the email problem is to restart JIRA. However the customer, and if necessary Atlassian Support, should also investigate to find out the cause of the OutOfMemoryError.

I would like us to update our documentation for both:

• Creating Issues and Comments from Email
• Configuring JIRA to send SMTP mail

to include a Troubleshooting section that covers this off. That is, tells the customer that if email handling isn't working, to check the log file for OutOfMemoryError. If there are OutOfMemoryErrors, restart JIRA. Then investigate the OutOfMemoryError, and create a support case if help needed.