Last reviewed on December 27, 2012   —  56 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.


  1. C Brown says

    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.

    • Diane Poremsky says

      I'm bot sure I understand - Outlook 2003 had problems with dupes too. It's made worse in Outlook 2010 if you deliver all mail to one pst file, but its not a unique problem to newer versions.

    • prince says

      I am really sorry, but you are blaming a Software Giant, for not having a tool to remove duplicate Emails. I understand your frustration, but let me tell you when you add or import the PST file there always an option if you pay little attention while importing the PST file (that says do not import duplicate) you will be at ease. the other thing is that, there are limitation with POP accounts, use an IMAP or EAS instead of a POP account and you will have all your device synced with each other, and will not at all have such problems, POP is an old concept and we can eliminate it as many of our customers are using an Old Email which only support POP, again the concept of POP was introduce because initially Email service provide hardly gave space to email holders and it was like 40 MB 70 MB and so on. and this is the reason Outlook was introduced so that it allows you to hold up your data on the PC and even when it reaches or exceeds more than the provide size.

    • Diane Poremsky says

      Sometimes the duplicates really are Outlook's fault - like when you leave mail on a pop server and create a new account. The do not import duplicates won't help in that situation. :(

  2. Chris says

    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 says

    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.

    • Diane Poremsky says

      If Outlook is more email/information manager than you need, Windows Essentials Mail is a lighter, more OE-like client that may meet your needs better.

      I'm not sure I understand the issue around downloading mail in one folder. Outlook will download all mail in your Inbox (when you use POP3) and they are only moved if you use Rules. There is an 'unread mail search folder' you can use to see all new mail in one folder.

      Other than these generic answers, I can't offer other suggestions without knowing more about your setup - what type of email account and how many accounts are in your profile.

  4. Jim says

    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.

    • Diane Poremsky says

      The sophisticated software needs to track the messages that were downloaded and there are a number of conditions that cause the tracking file to be corrupt. Outlook stores the file in the pst file - it is linked to the account that created it. If you make a new account, outlook makes a new file.

      Are you using IMAP or POP3? You can use IMAP to move the really old messages into a folder online to archive them. POP3 will only download what is in the Inbox, IMAP only gets subscribed folders. Obviously, you can't move mail to a folder if its not subscribed, but if you can most of the mail out of the inbox, it will be easier.

  5. Candai says

    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!

    • Diane Poremsky says

      Is the branch using an antivirus scanner on the desktops? Duplicate messages can result when sent mail is scanned by antivirus. Has the administrator checked the Exchange server logs to see if the server is receiving the copies? That will tell you if they are originating on the senders computer.

  6. Mark Warner says

    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?

    • Diane Poremsky says

      MSE is not involved. It may be happening because you are using one pst for all accounts and the mailbox manager file is corrupted. It's not unusual when you leave mail on the server. However, its usually more random and only affects secondary accounts, not the default, which leads me to think its a rule causing the duplication. Or its a catchall mailbox. Are any of the accounts in a catchall mailbox? Like maybe 3 accounts? Outlook downloads everything in a mailbox, it doesn't skip ones sent to another address, like some clients do.

  7. Mark Warner says

    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.

    • Diane Poremsky says

      It could be outlook or something with your configuration. Are the accounts on the same email sever or different servers?

      The imap accounts should have their own data file. If you are using rules to move the imap messages to a pst, disable the rules and see if they are duplicated.

  8. Steevo says

    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?

    • Diane Poremsky says

      Correct, its the client, because that is where the last downloaded id is saved. There are several things that will cause messages to redownload - because it keeps returning when you restart outlook tells me the message manager file is being corrupted and the last message count isn't saved when Outlook is closed. When it fails between send and receives, outlook isn't properly updating the message manager file - that is what the hotfix addresses.

      You could try using scanpst on the data file (or export to a new pst) or removing the account from outlook and adding it back. If you like digging on the technical side, you could use MFCMAPI to look at the stuff hidden in the data file and delete the mailbox manager file for the affected account. you may have several message manager files from previous profiles and removing them could fix it.

      Any of the potential fixes may cause outlook to redownload everything again, hopefully for the last time.

  9. Steevo says

    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.

    • Diane Poremsky says

      That's odd. It shouldn't even work with OE.

      Does it always download 75 or does the number increase as new mail hits the mailbox?

  10. Steevo says

    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.

    • Diane Poremsky says

      So it's only a set of older messages that keep downloading? If I'd send you a message today, that will only download once?

  11. Steevo says

    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 says

    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 account being checked. One other account has a couple of duplicates being downloaded but that account does not receive much mail.

  13. Steevo says

    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

    • Diane Poremsky says

      These errors relate to an exchange mailbox. Not sure why you're getting them, especially the last one.

  14. Steevo says

    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 says

    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.

    • Diane Poremsky says

      New mail is arriving ok? I'm surprised it's only getting that mail - it should be non-discriminatory and get all mail over and over when its not working correctly. It's possible that the older messages are corrupt in some way and that is confusing outlook.

  16. Steevo says

    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.

    • Diane Poremsky says

      It definitely doesn't make sense and it's not how download duplicates normally work - it's usually all or nothing, not pick and choose what will be downloaded again.

  17. Steevo says

    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 says

    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.

    • Diane Poremsky says

      This half sounds like the addresses weren't properly resolved - that would account for not being able to use them to send mail, but it doesn't explain the moved or deleted message. Unless it's an address in a contact list. To fix, you need to move the address out of the address field then move it back in and save. A macro can take care of this.

      What are you doing when you get the moved or deleted error?

  19. David says


    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?

    • Diane Poremsky says

      Honestly, if IMAP is supported, i would use it instead of POP. Changes will sync to the server and to the phones. Sent items will (in most cases) sync to the server and be accessible to each other. Categories won't sync, but if you move mail to other folders, it will be moved for both.

    • David says

      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 says

    @ 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 says

    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 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.

    • bonvie27 says

      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.

    • Diane Poremsky says

      Are you leaving mail on the server? Duplicates usually means the client isn't deleting mail from the server and isn't properly tracking the last message downloaded. it could also mean the server is doing something like changing the message id so the client sees it as new.

  22. Jaap Kuiper says

    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.

    • Diane Poremsky says

      Note, sync pst files using cloud services is not recommended. It can result in a corrupt pst file and data loss.

      (The ops file is an Office Profile Wizard file, used by corporations to preconfigure office for their users.)

    • Jaap Kuiper says

      I actually mean the .ops file you can generate with the office tool "backup my settings" (is it the same?). It saves all the pop3 information with the exception of your passwords. I've read that the .pst can get corrupted but still it is a nice solution when using 2 or more computers, each computer has it's own .pst stored locally in the dropbox folder. Although I regularly move (backup) email to other (non-dropbox) local .pst files you could always recover from a corrupted dropbox .pst file when you encouter one, simply go to the 2nd computer, disable any network before you power on your computer and backup the file in your dropbox folder before it gets overwritten with a corrupt version.
      This situation is great for me for working in two geographic locations with 20+ pop3 accounts. No need to carry a laptop on my bike anymore.

    • Diane Poremsky says

      It's built on the same technology - but it was removed from Office a few versions ago.

  23. Riviana says

    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

    • Diane Poremsky says

      Did you create a new account or new profile in Outlook? Did you run scanpst or another pst repair tool? How frequently are you checking for email? Set it to at least 5 min, 10 is better.

  24. Shrikrushna says

    I am using Outlook 2007 Configured with POP3 Account but Certainly Some Mails getting Downloading Repeat, Please Give Any Technically article it can Solve My issue...

    • Diane PoremskyDiane Poremsky says

      That usually happens when the internet connection is spotty or you are using an antivirus or antispam scanner to check mail as it's sent or received. Outlook and the server can't communicate properly and outlook doesn't know which message was the last one downloaded and downloads old messages too.

  25. WendyG says

    I recently switched from Outlook 2007 on a PC where I used POP email and left a copy on the server and NEVER had any problems with duplicate email downloads. Just got a Mac with Outlook 2011, moved my PST file from my PC over and loaded it. Set up my same POP Yahoo email and hit send/receive and it downloaded 20,000 emails from the server. I understood why it downloaded all my old emails into the newly set up computer. What I don't understand is why it keeps downloading those same 20,000 emails again and again each time I send/receive?? How can I get this to stop? I want to leave a copy on the server so I can access from my phone or web mail - this was never a problem before moving to Mac. Also, I read above to limit how often it auto send/receives but I can't figure out where to change this setting on Outlook 2011 for Mac? Please help. I called Microsoft but they want $99 to help with this issue.

    • Diane PoremskyDiane Poremsky says

      When a mail client keeps downloading mail over and over, it means its not properly tracking the last message downloaded. This is not uncommon when downloading a large number of messages. The mac will need to download all of the messages once - then it should only get newly arrived messages.

      One option is to move the messages into a new folder online - POP3 only sees what is in the inbox. I don't know how easy that will be to do in yahoo. The other option is to set up the account as IMAP and move the old mail to a new folder - the changes will sync back up to the server.

  26. CarolineG says

    I have the exact same senario as WendyG but it is happening when I take my laptop home and connect to a different wifi the download of 2000 messages on the server starts all over again. I have changed my settings to delete from the server after one month. Should I go in and completely clean off the server? I still think its related to the change in internet connection.

    • Diane PoremskyDiane Poremsky says

      Are you using a different profile or windows login at home? Outlook shouldn't redownload the message just because you changed connections but it will if you changed profiles.

  27. Jo says

    I have a PC & later purchased Apple iPad I have same email address on both plus a second on iPad but I never get the email on th iPad that I get on PC. Why?j

    • Diane PoremskyDiane Poremsky says

      Is the account set up as pop3? If outlook downloads and deletes from the server, it won't be available on the ipad or other devices. You can set outlook to leave on server or remove the pop account and add it back as imap.

  28. mohan says

    i have an issue whenever i start the outlook all mail of inbox is getting downloading in outlook. outlook configured in pop..please suggest ....

    • Diane PoremskyDiane Poremsky says

      What version of Outlook? Did it work correctly before and now isn't?

      When this happens, it means Outlook isn't properly talking to the server and marking the messages that it downloaded or deleting from the server (if you aren't leaving mail on the server). This can be caused by a bad internet connection or temporary problems on the server, or the pst has some corruption and outlook can't properly save the file that keeps track of the messages it already downloaded.

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