It does appear that the JIRA Mail Handler currently has no way of keeping track of emails it has attempted to process (after it fails to process this emails correctly for any of various possible reasons), and so it goes into an unending loop of trying to re-process the email. This could have various undesirable effects as has been reported in other bug reports e.g. duplication of issue creation, endless logging about the failed attempts etc.

Usually the workaround is to manually remove the problematic emails, but this is sometimes inconvenient, as the problem could go on for a long time or over an entire weekend before someone is able to manually intervene.

Perhaps we could device a better handling for this kind of emails e.g. set a limit to the amount of times JIRA would re-attempt to process a specific email, and ignore that email after these number of failed attempts or take some other action to prevent the endless loop.