"comment by email" feature has been enabled for jira running at issues.jboss.org during today's outage.

It means you can reply to a notification email received from jira, and your text will be added as comment for the issue received email was about.

"Add a comment from the non quoted email body" handler is used. This message handler creates a comment, but only uses the 'non quoted' lines of the body of the email message. A quoted line is any line that starts with a '>' or '|' symbol and such lines of text will not be added to the comment. The issue to which the comment is added is chosen from the first issue key found in the email subject. The author of the comment is taken from the address of the email message's From: field. Messages from unknown email addresses are ignored silently.

As part of this task we have to change email address JIRA uses as From in emails to issues@jboss.org

You have to upgrade your "from JIRA" email filters if they depend on it.