Microsoft Outlook – duplicate email messages Part I

This will likely be a multi-part story because it turns out the solution was one of the more obscure things I think I’ve run into AND I thought it was worth “dumping” everything I found out in the process here for my own reference and anyone else wandering through. I have a customer that uses Microsoft Outlook 2003 and has selected to “leave messages on server”, then delete them when they’re deleted from the recycle bin. This normally works well, although I do recall one (or two) instances in the past when he got duplicates.

The main reason for doing this was to allow access to messages (even older ones) via webmail while on the road. Seems reasonable. The time came that he migrated webhosts. All of the changes were made, new account settings added to Outlook/old account settings were disabled, but kept for the time being. Within a week he reported having a batch of duplicate mail messages. So the quest for a solution begins….

First stop, checking the webmail. No duplicates there. (So the server isn’t actually delivering a second set of messages.) Ok, some googling later. It looks as though there are a number of things that can cause Outlook to get duplicate mail messages. Among other things, I found it’s such an issue that there are beacoup pieces of software out there to attempt to fix it. (Not a good sign…)

So, first off I found one software company that had some tips. Among them…

Make sure that all rules end with “Stop processing”

Make sure only one copy of Outlook is running
Delete ALL mail accounts and re-create them
(I found another tip suggesting using a different name for the account)

Upgrade to SP2 or later if running Outlook XP

Under some circumstance with two mail accounts setup, both using the same POP and SMTP servers you may receive duplicates as described in this knowledge base article (284404)

Well at this I’m loaded for bear for the first visit. No duplicate process of Outlook, no reports of crashes of Outlook. Remove email accounts, recreate one single account for the new server, check rules to verify they all “stop processing” and enable diagnostic logging as described in this article “How to enable transport logging in Outlook 2002 and Outlook 2003”. Nothing unusual while onsite.

Within 24 hours, yet another instance of duplicates had occured. Hmmmmm…..

More searching. Here’s the next stage of stuff I find…

Duplicate e-mail messages are downloaded from a POP3 e-mail server account in Outlook 2003 This seemed to describe the EXACT problem, duplicate messages downloaded when “leave a copy of messages on the server” is checked. It described a hotfix 885243 that would solve the issue. Sounds promising, but I wanted to be prepared with more than one possible fix.

I found the following suggestions:

You can follow Microsoft’s instructions to turn off reception of messages for duplicate account settings, if any, Password Prompt, Duplicate Messages Appear If Outlook Profile Has Two POP3 Accounts (KB284404)
You can follow Microsoft’s instructions to upgrade Outlook to Service Pack 2 (SP2) or later, Mail Retrieval Problems Occur When You Receive POP Mail (KB317945)
You can read Microsoft’s description of a timing issue that can result in this problem, Outlook Downloads Messages from a POP3 Server Twice (KB292249)
You might also wish to look at suggestions 3 through 6 in a listing of ways to troubleshoot duplicate messages in Microsoft Outlook 2002, provided in a November 2003 memo, Outlook XP Downloads Duplicate POP3 Messages by Pamela Y. C. Fong of the California Institute of Technology.

From the Cal-Berkeley campus mail troubleshooting tips. Let’s see, we’ve cleared KB284404 on the last visit, I’m reluctant to go the full service pack route yet. Timing issue sounds new though. KB292249 refers to a situation where the sync process takes place during an emptying of deleted items, duplicate messages could be re-downloaded. (Instead of deleted). That’s a possibility. On yet another site, I find a suggestion of too frequent mail checks being a culprit.

Yet another page suggests these causes:

KB292249: Outlook Downloads Messages from a POP3 Server Twice;en-us;292249

KB317945: Mail Retrieval Problems Occur When You Receive POP Mail;en-us;317945

KB284404: Password Prompt, Duplicate Messages Appear If Outlook Profile Has Two POP3 Accounts;en-us;284404&Product=ol2002

KB289942: POP3 Headers Are Duplicated;en-us;289942&Product=ol2002

Using Anti-Virus Software
Many of the anti-virus programs that scan email can cause this issue as well. When the messages are large, the software causes a ‘timeout’ to the server before it sends back a flag that id’s the message as being read. As a result you recieve the message over and over.

Most are what I’ve seen before, but the antivirus software is a different one. OK, just to cover the server end I contact the webhost tech support and, as expected, hear. “This is usually caused by Outlook’s handling of messages, here’s a knowledge base article if you have further problems contact Microsoft for support.” Finally I press and ask if they know of ANYTHING server side that could cause it and the answer is a flat no.

So, back on site… I decrease the frequency of mail checks from 5 minutes to every 12 minutes. I call Microsoft at 1-800-642-7676 for access to the hotfix #885243 and install it, I email a copy of the OPMLog.txt to myself to analyze. Increase server timeouts to 10 minutes as suggested in an above link and make sure the antivirus isn’t acting as a proxy for scanning incoming messages. I create a link on the desktop to the OPMLog.log (opmlog.txt ?) and give instructions on how to email the contents to me if it happens again.

A day goes by, then two and I’m thinking it’s licked… but on the third day. Duplicates again. I ask for the log. Later that afternoon I receive the log (too late, Outlook has already recycled it and the transaction that had brought duplicates is not in the log.) I make it clear that I need the log as soon as possible after the duplicates happen and that the only thing I can do until then is the SP2 update to Outlook (Office) 2003.

I had already looked through the first (and so far only) logfile to figure out what went wrong. The transactions seemed normal until Outlook started downloading messages. I backed up and looked at the entry previous and it didn’t seem out ofthe ordinary…. to be continued….

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