Problem

The below message appears at atlassian-jira.log. The message you are seeing comes from AbstractMessageHandler in the jira-mail-plugin. In case if JIRA receives an email from another JIRA instance.  It means JIRA sends X-JIRA-FingerPrint included in the mail header.

 Received message with another JIRA instance's fingerprint

Cause

This feature is to detect loop and avoiding it.

See the Email class:

 public class Email extends com.atlassian.mail.Email
{
    /**
     * JIRA's custom mail header used to contain a magic fingerprint string "unique" to a JIRA instance, used for
     * identification purposes.
     */
    public static final String HEADER_JIRA_FINGER_PRINT = "X-JIRA-FingerPrint";

Here is where the message comes from:

if (!fingerPrintHeaders.isEmpty())
        {
...
            if (fingerPrintHeaders.contains(instanceFingerPrint))
            {
...
            else
            {
                log.info("Received message with another JIRA instance's fingerprint");
            }
        }

Workaround

• If willing to create issue when another JIRA send to another JIRA's mailbox, it can't be achieved by JIRA's default setting.

• Workaround is to modify the code which removes your instance from Atlassian Support Offerings.
• If this issue is critical for your operations, a feature request ticket has been created at JRA-44107 - Getting issue details... STATUS . We would like to encourage you to cast a vote on that issue and share your use-case within the comments, as that has way more impact on our product development than most other efforts. Also add it to your watch list to get notified once it is implemented in a future version.