Outlook is downloading duplicate emails from a POP3 account

Last reviewed on December 27, 2012   —  46 comments

Outlook users complain when Outlook downloads duplicate messages when they re-use Outlook data files. This is expected behavior when you use an old pst and leave mail on the server.

I moved my pst files to a new computer and set up Outlook to use the old pst files. When I try the first send/receive, Outlook downloads all of the emails off of the server even though I already have copies in the inbox. How do I get it to stop downloading the copies of the email? If I can't, how do I sort the email for the newly downloaded identical copies and delete them?

Duplicate remover utilities are available at Duplicate Remover Tools

You can't avoid Outlook downloading duplicates when you leave mail on the server. The "Mailbox Manager" file Outlook uses to keep track of messages that were downloaded is associated with the account that created it and downloaded the mail. When you create a new account, Outlook has to re-download all of the mail again.

There are ways to deal with this issue though:
1. Because POP3 only downloads mail that is in the Inbox, you can move the mail from the Inbox to another folder in your account online (log in using webmail) before taking Outlook online.

2. Let Outlook download the mail then add the Modified date field to the view, sort by it and delete all of the mail you just downloaded (that was previously downloaded.)

To add the Modified date field to the view and delete the duplicate messages:

  1. Close the Reading pane
  2. Right click on the row of field names and choose Field Chooser
  3. Select Date/Time fields from the drop down
  4. Drag Modified to the row of field names and drop it between two fields.
  5. Click on Modified to sort.
  6. Select the first message you downloaded in the session
  7. Scroll to the last (or last non-duplicate), hold Shift as you select the message
  8. Press Delete.

3. Turn off any rules you use and move the contents of the Inbox to a temporary folder. Download mail and delete the old mail from the Inbox. If you use Outlook 2007 or up, you don't need to move your mail our of the Inbox; you can choose a different folder as the delivery location in Account Settings, select account > Change folder.

Add a new default delivery folder

4. You could use a duplicate remover tool to remove the duplicated messages. But honestly, that's not necessary.

Written by

Diane Poremsky
A Microsoft Outlook Most Valuable Professional (MVP) since 1999, Diane is the author of several books, including Outlook 2013 Absolute Beginners Book. She also created video training CDs and online training classes for Microsoft Outlook. You can find her helping people online in Outlook Forums as well as in the Microsoft Answers and TechNet forums.

Please post long or more complicated questions at Outlookforums.

46 responses to “Outlook is downloading duplicate emails from a POP3 account”

  1. C Brown

    This response suggests that we constantly do manually what outlook 2003 handled with ease!
    Removing email from the server each time we download means we can only access our email from one device. Once I've downloaded email at home, I can't access it from work, for example.
    This should feel shameful to Microsoft.
    The only thing that could make Apple's Big Brother approach look good is Microsoft's FU approach.
    Everything on Windows 8 takes twice as many clicks.

  2. Chris

    I have no problems with this setup on any of my 2003 or 2007 Outlooks. Every one of my 2010 Outlooks is receiving duplicates or not downloading the messages from the pop server at all. 2007 was definitely a much better product.

  3. leo

    The best email platform was Outlook express. Who ever decided to stop this platform instead of refining it further has committed a crime to the IT world. Instead we have to put up with an inept platform called Microsoft outlook a product that has complicated everything. Why it does not have an easy option to ask it to down load all emails in one folder. So one chases emails in several folders without any logic as to why it places them there. It must have been designed by IT people who don't have any understanding of customer service or any idea on simplification or human thinking.
    Disgusting really. Microsoft outlook is in immediate needs for workability and functionality through simplicity. AS for the matter of down loading two identical emails of each email its just ineptness to the extreme particularly as there is not an obvious simple option to fix it. An outcome of monopoly.

  4. Jim

    I agree with Leo. This is programming ineptness. Why a sophisticated piece of software can't determine you already have the message and not download it again, and update its record of same is just beyond belief. I have been struggling with this on an account that has 65535+ messages on the Yahoo server since last Weds .. and just when I think I have it working, it wants to download them ALL again. Good grief.

  5. Candai

    Ours is quite different where our branches use POP3. Now when the branch sends to another staff at H/Office who is using normal Outlook 2007 client in cached mode, the client receives almost 10+ copies of the same email. This happens to at least 1 or 2 POP3 users at the branch when sending to multiple recipients at HO. Please help!

  6. Mark Warner

    I'm using Outlook 2013 with Microsoft Security Essentials. I'm getting 3 copies of each email that is downloaded from the pop servers. I have multiple accounts all going to the same PST file, and all accounts are doing the same duplication. How can I prevent/fix this?

  7. Mark Warner

    All 5 of my mail accounts are going to the same PST file. 3 pops and 2 imaps. The duplicates that are coming in are the exact same email going to the same account. I've checked the email pop server before hitting the send/receive and the email isn't in the pop server more than once, so I'm thinking it must be something within Outlook 2013.

  8. Steevo

    I have been leaving messages on server for literally years, and I download them on 4 or 5 different computers, this way I have a complete set of my emails at every computer I use. It's my backup system.

    This is a part of the normal email system and on a couple of computers I use a very old version of eudora which handles this all properly. It's not a server thing, it's a mail client thing.

    I think your assessment of the problem with Outlook 2003 is wrong. There is a tech note on it.


    I installed office 2003 on a new computer, migrated with the files and settings transfer wizard, and all that worked, except for the upgrade to Outlook 2003, that is.

    I followed the procedure on the tech note and the problem was partially but not completely resolved, I uninstalled and reinstalled Office, it got better but I still have one mailbox that keeps getting the same messages but only every time I restart Outlook 2003.

    Clearly the database that Outlook 2003 is using to keep track of what messages have been previously downloaded is not working properly, and that is what needs to be fixed. Do you have any suggestions to repair that database, or recreate it?

  9. Steevo

    Well, I tried MFCMAPI, but it seems to only be able to see my OE profile. It can't see that I have an Outlook profile- nor does it seem to be able to be told to import a pst I point it at. As I mentioned I transferred this all with the files and settings transfer, and then I imported into Outlook. The old system was only OE.

    I looked at scanpst but the PST I have is 4 GB. It's been around a while. So that is past the limit for that tool according to what I read.

    So I exported the bad folder, reimported it to a new folder, and I have the same 75 duplicates being downloaded to the new folder. So I just dunno. None of this is working for me.

  10. Steevo

    No, the number is diminishing as time goes on and the messages fall off the server as their time runs out. So this will likely resolve itself after all messages that are 10 days old are removed as asked.

    That said, I do like to solve problems as time allows.

  11. Steevo

    Yes, there is a range of dates that are exhibiting the problem and it's getting smaller as the older ones are removed from the server.

    I have 10 separate mail accounts on outlook on various servers, and this problem was on all of them when I first started, but following the tech note and reinstalling outlook seems to have resolved the problem for all but one or two pop accounts. All were set to leave mail on server 10 days.

  12. Steevo

    Well, I was wrong.
    MFCMAPI does indeed find and work with the Outlook PST file.

    I just restarted and I have duplicate messages through today, so I thought they were timing off but they are not. This is just one folder which constitutes one att.com account being checked. One other account has a couple of duplicates being downloaded but that account does not receive much mail.

  13. Steevo

    With MFCMAPI, MDB/open other mailboxes returns errors. One, two or three.

    Code: MAPI_E_NOT_FOUND == 0x8004010F
    Function HrGetOneProp(pGlobalProfSect, PR_PROFILE_HOME_SERVER, &lpServerName)
    File MAPIStoreFunctions.cpp
    Line 337

    Code: MAPI_E_NOT_FOUND == 0x8004010F
    Function GetServerName(lpMAPISession, &szServerName)
    File MAPIStoreFunctions.cpp
    Line 655

    Code: MAPI_E_NOT_FOUND == 0x8004010F
    Function OpenOtherUsersMailboxFromGal( lpMAPISession, lpAddrBook, &lpMailboxMDB)
    File MainDlg.cpp
    Line 728

  14. Steevo

    I ran scanpst on the pst file, and it found and fixed some errors, but the problem still exists, on a restart of outlook I get the same 80 emails, including a few new ones in the last couple days.

    MFCMAPI still shows several quite cryptic errors when I click open other mailbox.

  15. Harry Mercer

    I have anew laptop with Wndows 8.1! My e mail is now on M/S Outlook. I keep getting old e mails no matter how often I delete them. These are mainly from 2010 which I am sure were deleted from my Outlook express. I heartily agree with the comments about replacing Outlook Express. can you tell me why 2010 seems to be the culprit year.

  16. Steevo

    I still have some duplicate emails. Only on restart of outlook. It's pretty interesting, I get obvious duplicates dates on one date, then a day or two later, some more. I just got 20 duplicates of emails that came in today.

    Only on a couple of accounts, the rest are fine.

    I wish I could make anything out of the data from MFCMAPI, but I don't see the bad account name to look to see what the problem is. As I said, I created a new folder, exported and then imported the entire mailbox into the new folder. That didn't change anything at all.

  17. Steevo

    Well, I am about to give up and try to eviscerate this installation completely.

    One other problem I noticed was the address book, though it's large and has many addresses, came from OE, though I can click on it and see it, none can be used to send mail. Which seems odd. Something is just not right. Nothing I have done has fixed this at all.

  18. Steevo

    It says the contacts associated with this address list may have been moved or deleted. When I click on contacts, they are there. When I click on OE contacts, which is where they came from, nothing. Odd.

  19. David


    I have a less complex version of the same problem. My wife and I have a POP3 account that we both access from our unique profiles in Windows. I created a single PST so that we could both categorize and sort read messages. We both use our smartphones to access the shared account as well, so the option to leave messages on the server is a must. The intent was to recreate the "Organizational Mailbox" environment that an Exchange user would have, whereby it's easy to see what messages have already been acted on. Problem is if I check the account for a few days, sure enough, as soon as she goes to check the mail, she gets a "fresh" copy of everything I've already worked on. Frustrating to say the least.

    I've read through this entire thread and, I don't see the silver bullet solution--unless I were to purchase an expensive and unnecessary email platform for home use. Your proposed solution is great for me because I work in IT but, lousy for my wife, who'll want to know why she's seeing double. In this setting, I'd like to think of my wife as the end user who doesn't want to be bogged-down with Band-Aid fixes that she has to apply every time she logs on. She (like most end users) wants an appliance that functions without having to "jiggle the cable."

    What can you offer in the realm of user-friendly?

    1. David

      Diane, this was a life-saver! I can't believe that I sat back and ignored the IMAP option all this time. Funny thing is, it started working so perfectly that I changed it on all of our devices and platforms (including yahoo) and forgot to get back on here and thank you for offering simple yet wonderful solution. Thanks again.

  20. Himesh Shah

    @ Ms. Diane Poremsky : Thanks a million for this post. I cannot explain in words how much this post of yours helped me in solving my problem.
    God Bless You!

  21. Duggie

    I can't believe this is still going on - this problem has been around for several years, and there is only ONE source to blame - Microsoft. I have a number of laptops and a couple of different mail servers, and I also have a yahoo.co.uk email account, all of which I created accounts for on my ipad, iphone 4, Windows 7 Ultimate laptop, and Macbook Pro. As far as the Windows 7 machine is concerned it runs Outlook 2010 and I have no problems on it whatsoever. I also have no problems on the ipad. However, on the iphone and the Macbook running Office 2011, I have a mega email download around every 12 months.

    All the excuses made earlier in this thread are simply trying to divert the attention away from Microsoft. I paid good money to BUY this Office 2011 product - which is licenced by Microsoft. So WHY is someone trying to take the blame away from them when they are charging everyone to use the software which is obviously not fit for purpose?

    Does everyone have the time to start messing around writing scripts or creating rules etc just to give themselves a 'fix' for a problem caused by Microsoft? Well, I don't!! It's ridiculous to even suggest that the paying customer should have to 'fix' or work around problems caused by Microsoft.

    Also, to suggest that people should have to move to IMAP instead of POP3 is ridiculous. Why on earth should someone have to change the way THEY decide to work just because Microsoft refuses to spend some of the trillions of dollars profit on making their software work? I'll find a work around - and it won't involve using Microsoft products.

    There are many different email clients around, and as my Macbook has just started to download several thousand emails again then I can assure everyone reading this that Outlook 2011 will NOT be remaining on my Macbook for much longer.

    My days of paying for inadequate Microsoft software are over. As a software engineer myself, I do understand the need for software to be properly licenced, but I draw the line at being ripped off by having to pay for software that simply does not do what it's supposed to do.

    For all those who are 100% Microsoft through and through, fine - you choose to be loyal and you believe what you want to believe. But I believe they have wasted far more of my time and money than any other organisation I have ever encountered, so I refuse to financially support them any further.

    1. bonvie27

      Reply to Duggie:
      Suddenly a couple months ago started getting duplicate emails on my POP acct in Outlook. I then tried several other email applications (airmail, postbox, etc.) but they are all giving duplicates. Reason for my reply is what the heck to do? You said you will not use Microsoft, and I agree, but all my alternatives so far have not solved the issue. I do not want to learn to be a computer programmer. Those guys are supposed to have tested this, since it seems to be an ongoing issue.

  22. Jaap Kuiper

    I was having problems syncing my .pst from dropbox. Every pop3 account with the settings 'leave messages' on the server for x days would give me duplicates every day. The problem was I created each account on each computer MANUALLY. When I deleted all my accounts and imported them using the .ops file from the other computer my problem went away. I guess Microsoft uses a specific number that links to each account which tells the master file if a message has been downloaded or not. When you import the .ops file you get the same number for your accounts, when you create them manually on each computer they will have different numbers ad therefore will always be out of sync.
    Hope this helps somebody.

  23. Riviana

    I have not reinstalled Outlook , still it is downloading all the emails again from the server. How do i stop that ? I am using Outlook 2007

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