Upgraded from office 2003 to Office 2007. Certain e-mails which have large distribution lists continue to populate the inbox (like 12,000 plus copies of the same e-mail). When I log into the web interface I can see the single e-mail in the inbox, but it is never removed. If I delete the duplicating message from the server via the Web interface I stop getting the duplicate messages on the Outlook 2007 client.

Hi, I understand that you have have duplicated messages only in outlook, is that ture? Then please try to export the message to pst and then delete all the messages in inbox and then import pst to inbox. Xiu