Outlook POP3 ‘duplicate messages’ and issues sending and receiving to a 3rd party POP3 server (messages stuck in the outbox)

Here’s an interesting one, with a simple fix. A customer called today and they use Outlook 2003 with a 3rd party/hosted POP3 Server (and frankly, this problem and resolution could apply across all of Outlook, POP3 Servers and under the heading ‘common sense’). They have the option in Outlook to ‘Leave a copy of messages on the server (see screenshot below), so that they can still see recent messages on their hosted ‘webmail server’, from a web browser.



The Symptom

The symptom, in this scenario is that frequently:

  • Messages would pile up in the Outbox and would not send/deliver, until Outlook was closed (completely, gone from task manager) and then reopened
  • Some messages would arrives as duplicates, in the Inbox


The Solution

The solution was to address the problem – PEBCAK (Problem Exists between Chair and Keyboard). The problem was the ‘Send/Receive’ settings in Outlook were set FAR too aggressively. Send/Receive was scheduled to occur every minute. This meant that by the time the POP3 server had attempted to deliver messages, it was already instructed to open a new session and do it all over again. Effectively, the server would never get an opportunity to ‘mark’ the messages as complete, or close the session, resulting in frustrating and inconsistent results.


Choose Tools, Send/Receive, Send/Receive Settings, Define Send/Receive Groups…


Set the Send/Receive Automatically to a *reasonable* timeframe. 10 minutes is aggressive enough while still allowing the server to function properly – a good compromise between being ‘busy’ but not ‘nuts’. This was set to ‘1 minute’ in the scenario above. If the user *really* wants a message now, they can pound the ‘Send/Receive’ button, as needed.