Duplicate emails from groups

Question

I use POP3 to download email to outlook. Certain emails that are sent to groups of 10-20 people show up as duplicates in the outlook 2010 inbox of some recipients, as well as the web interface that hosts the email. I've made sure that the groups don't contain multiple entries, and that no aliases exist in the groups that point to the recipients having issues with duplicate emails (like [e-mail] having [e-mail] alias and both being on the group).

What are some common causes of email duplicating in the scenario described above.

Answer 1

This is a support article from Microsoft that discusses the duplicate email issue in Outlook 2010:

http://support.microsoft.com/kb/2685726

The main issue they site is that the Outlook client is looking for mail before it completes a full check for any new mail. If the message is not marked delete before it finishes this check then it could download the same resulting in duplicates.

Another thing to check from my experience if you are using Exchange is to run Message tracking against one of these emails. Verify the email server is only sending a single copy of the email message. If the HUB server is duplicating the mail then it is a sign that it is a problem at the server level and not the client level.