I created several users with the my email address. The first was noaa.test.user. I was able to submit email through the email handler and not surprisingly the reporter was noaa.test.user.
So I removed authorizations from noaa.test.user. I removed access to JIRA and all group memberships.
Now the email handler is ignoring email messages from my address, even though I still have authorized users with that address.
I have demonstrated that I can fix the problem by changing the email address of the unauthorized users to an address that will never match any incoming messages. Then the address of an authorized user will be found. This is an adequate solution, so you can close this issue.
But... it seems like a bug to me, you may want to notify the developers.