Customer getting duplicate emails

[Az]

A customer for a project is getting duplicate emails from JIRA. They are the only customer on this projects. 

This is happening for all emails they get. An example of this is when a public comment is added. This is my customer notification setting for that 

I thought it might be an organization thing, but I removed the customer from the organization and the organization from the task and the customer is still getting emails. 

I'm out of ideas on what this could be. No one else is getting two emails. 

[Az]

@Andy Heinzer

I thought that could have been the case as well, but these are legitimate duplicates. It happens even with just a comment - no transition or anything else involved. The emails are identical. 

The user is not a core of licensed user.

[Andy Heinzer]

Can you let me know what version of Jira and Jira Service Desk this is?  I am curious to see if perhaps we have a documented bug that might effect specific versions.

In addition, I would be interested to see if perhaps you can enable debug logging for Outgoing mail in Jira per https://confluence.atlassian.com/jirakb/how-to-enable-debugging-mode-for-emails-816520648.html and then see if you can recreate this problem once more.  I am interested to see if the execution time between messages has any pattern that it follows, or if the specific actions in question (like an issue transition, or comment) might be a factor in this happening.

These logs would then appear in your $JIRAHOME/logs/ folder.

[Andy Heinzer]

I would want to learn more about the specific emails received.  Sometimes users report these are duplicates, however frequently what can happen is that an issue changes a status and a comment is added at the same time.  These can count as two different events in Jira, hence there could be two separate mails sent out at approximately the same time, but these would have different bodies that indicates the specific change.

I just want to clarify exactly what these messages look like.  Another possibility is that the user could be received both Jira Service Desk and Jira core notifications.  If this user is also a Jira Core or Jira Software licensed user, then they can also receive non-service desk specific notifications depending on the project's notification scheme.