Symptoms

Application logs contain numerous occurrences of the following statement:

2023-12-15 13:01:47,970+0000 WARN [greenmail] Caesium-1-4 anonymous    B Received message carrying this JIRA instance fingerprint (7f7ffd1d5c43de0c061264d8cad4aaaa) 

In addition to the logs mentioned above, Jira may be processing incoming emails slowly or not at all.

Lastly, the following email might be received:

This is an automated email from the issue creation service at "<JIRA_BASE_URL>".

An error was encountered whilst handling messages from the mail server
"XXXXXXXX" using the handler "class com.atlassian.jira.plugins.mail.handlers.CreateOrCommentHandler".

The error was:
------------------------
"Message appears to have been sent by Jira. Jira's mail handler is configured to forward these messages to avoid mail loops.
"
------------------------

The error and the email that caused the error are attached to this email.

If this is a recurring problem, you may wish to contact a system administrator to check the parameters of your mail fetching service:



--
This message was sent by Atlassian Jira
(v${build.version}#${build.currentBuildNumber})

Cause

The Jira Mail Handler code detected a possible looping of emails. Since version 3.13 of Jira, every outgoing email is tagged with a custom header identifying the instance that is generating it. If any message containing such a header appear in any of the monitored incoming mailboxes, Jira will log a WARN message and send a copy of the mail to the Forward: address defined in the mail handler configuration.

If the mail loop is the cause, Jira may end up processing incoming emails slowly or not at all. 

Resolution

Identify and remove potential loop conditions such as:

1. Remove the Notification schemes associated with the project as described in here.
   
   • This is to stop the mail looping if there is any user account with the same email address of an email handler service.
2. Check if there is any user accounts with the same email address of an email handler service.
   
   • Search for the IMAP/POP server address in the User Management page
3. Make sure the Forward Email option configured in the mail handler is not the IMAP/POP server address
4. Check if there are any automatic response systems under administrative control which respond to emails from Jira.
5. Change the email address associated to the user account causing the problem to a dummy address