Why Am I Getting Duplicate Messages in Outlook?
Posted by Support, Last modified by Support on 01 September 2009 06:57 PM
Outlook downloads messages from a Post Office Protocol 3 (POP3) server again after it empties the Deleted Items folder even if you have both the Leave a copy of messages on the server and the Remove from server when deleted from Deleted Items options enabled on the POP3 account. Another possibility includes that there could be a corrupt email message in your inbox.
This problem occurs because a background synchronization took place at the same time or just after the Deleted Items folder was emptied. This is an issue with the order in which Outlook carries out the deletion from the server and the downloading of messages.
There is not an available workaround for this problem other than not to begin a synchronization at about the same time that the Deleted Items folder is emptied. This issue does not result in data loss (other than messages that you instructed Outlook to delete). Simply delete the duplicate messages.