One of my users is experiencing an issue where they receive duplicate emails from the same sender. I've checked the EAC message trace and noticed that there are two different message IDs for the emails, both received at the same date and time. One shows both 'receive' and 'deliver' events, while the other only shows 'deliver.' I've also confirmed that there are no mail flow rules set in EAC or Defender that could be causing this. I've done some research but haven't found a solution yet. Does anyone have insights on why this might be happening?
2 Answers
It sounds like the problem could be on the sender's end. If they're sending the same email twice with unique message IDs, there might be an issue with their email setup. It might be worth checking if they have any configurations causing this.
I once encountered a similar situation where an email rule was set up to send a copy to a signature service. As a result, everyone received two copies: one with the signature and one without. It's a good idea to see if a similar rule is affecting your user's emails. Often it's a misconfiguration on the sender's side, potentially linked to an inbox rule or some sort of relay issue.
Yeah, that might be the case! The fact there are two versions points to something like that. I'll have the sender check their configuration.