Article ID: 2685726 - View products that this article applies to.
If you're receiving duplicate emails, start at the top of the list below and work your way down. We’ve listed the most common cause first and worked our way down to the least common cause. If something jumps out at you, by all means go there first.
If you have "Leave copy of message on server" checked.
Check for duplicate mail accounts.
If you have a large amount of mail, store copies of it on the server and have Outlook check for new mail every few minutes, there's a good chance you will get duplicate email. Outlook will never complete a check mail pass before the next one starts, this prevents Outlook from marking the mail as downloaded. Try extending the time interval that Outlook checks for mail:
Optimize your Rules configuration.
Firewall or Anti-Virus protection settings could be set to high.
Get help from the Microsoft Community
(http://answers.microsoft.com/)online or visit contact Microsoft Support
(http://support.microsoft.com/contactus/?ws=support)to learn more about your support options.