One of our users is experiencing multiple copies of a single message when she downloads the message to her Outlook 2003 client. In her account setup, "Leave a copy of the message on the server" is not selected, and we have verified in the maillogs that the message is only being delivered to the server once (The message headers are exactly the same in all of the messages). We've turned off her client side Norton Anti-Spam. It happens randomly and the duplicates always appear in rapid succession, ie it's never a case that she deletes the message and it re-appears later. Rather it appears that the mail client randomly copies the downloaded message several times.

She is presently setting up another client on the same work station and another POP3 account on another server to help troubleshoot. Does this sound like it could be an ISP related problem? She's on a DSL wireless network in NYC. Mail server is Qmail, server os is slackware.