Remove Duplicate Mails in Microsoft Outlook

Martin Brinkmann
Apr 14, 2007
Updated • Mar 16, 2014
Email, Microsoft Outlook

I'm not a big fan of Microsoft Outlook but I have to use it at work because of corporate policy. Next to Microsoft's Internet Explorer 6,  Microsoft Outlook 2003 is having a top spot on my "software that I do not want to use but have to" list. Some guys at work like the Outlook software and use it at home as well while I'm happy to use Thunderbird at home feeling more at ease with this excellent email client.

Nevertheless I have to cope with certain situations and one is that Microsoft Outlook creates duplicate emails from time to time due to various "hick ups". If you take a look at Microsoft's knowledge base you soon find out that it lists several situations where Outlook may download the same email message more than once. I listed some of them for your convenience in the next paragraph.

  • You are prompted for your password, and you may receive duplicate e-mail messages if your profile has two POP3 accounts in Outlook (link)
  • Duplicate e-mail messages are downloaded from a POP3 e-mail server account in Outlook 2003 (link)
  • Duplicate junk e-mail messages appear in the Junk E-mail folder in Outlook 2003 (link)

This are just some of the knowledge base articles that you can find searching for duplicate mails in Outlook 2003.

The same applies to other versions of Microsoft Outlook including 2002 or newer versions such as Outlook 2007 or 2010. Now to clear the duplicate emails you can use the free software Microsoft Outlook Duplicate Items Remover. It scans a selected folder for duplicate emails and moves them to a separate folder where you can delete them easily.

ooutlook duplicate items remover

This is by far the easiest way to cope with this situation. The software does not only remove duplicate emails in Microsoft Outlook but also duplicate notes, contacts, calendar entries and tasks making it pretty universal for all things duplicate in the messaging software.

To use the program simply select a folder displayed by the program after you have installed it on your system and hit the remove duplicate items button afterwards.

The dupes are not deleted right away but moved into a subfolder instead so that you can go through the listing to make sure that there are no false positives before you hit the delete button.

Note: The program is not compatible with Office 64-bit versions. It is however fully compatible with 32-bit versions of Office running on 64-bit versions of Windows. It also needs to be noted that the program is not compatible with Office 2013 yet.

How the program determines if an item, a message, note or task for example, are duplicates? It verifies that all of the following information match each other:

  • For contacts: first and last name, company name and email address.
  • Appointments: subject, start and due date, status.
  • Tasks: subject, start and due date, and status.
  • Notes: contents and color.
  • E-Mail or Post: for received messages the Internet message ID; for sent emails the email subject and the time the email has been sent; draft emails subject only.
Remove Duplicate Emails in Outlook
Article Name
Remove Duplicate Emails in Outlook
A guide explaining how you can remove duplicate emails and other contents such as contacts or notes in Microsoft Outlook.

Tutorials & Tips

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  1. larson said on October 12, 2015 at 5:30 pm

    try this DuplicateFilesDeleter

  2. Daryl said on October 8, 2012 at 9:30 pm

    I’ve run this without problem in Outlook 2010 on a Win7 Pro PC.

  3. Dramatic said on October 20, 2011 at 10:04 am

    AviraWebFilter reports ODIR downloadsite as potetially dangerous because of malware. ^^ No wonder it’s free. ^^

    1. Tim Nash said on October 20, 2011 at 2:42 pm

      Doesn’t matter what some webfilter reports…scan all your downloads before installing and you won’t have to worry. My ODIR has worked great and no malware, etc…you must be the competition trying to defame a great piece of software.

  4. Ali said on June 25, 2011 at 4:49 pm

    This is really cool….

  5. Tim Nash said on April 28, 2011 at 10:13 pm

    Ummm, I can pretty much guarantee that if you are getting an Outlook 2007 crash after installing you are running a 64-bit MS Office version. You were warned right in the download page of their website: .

  6. Brooks said on January 20, 2011 at 12:47 am

    in our office we use office outlook 2010,
    I also have a copy of Thunderbird.
    it has a free add on for duplicate email remover i open it once a week and run it or if it needs to be dun.
    then continuing using office as normal

  7. j said on April 26, 2010 at 12:04 pm

    ODIR worked great with windows 7 and outlook 2007 ultimate. Just make sure you’re up to date with the SW.

  8. Steve said on April 25, 2010 at 4:12 am

    Due to my system fatally crashing (I blame the broken hibernate feature in Microsoft Vista), I am currently jumping through hoops to restore my email in Outlook 2007. Dear God Microsoft has fouled up Outlook! The functionality to restore from a PST is flat out bad. My system needs 2 email accounts and the restore feature isn’t smart enough to know under which account to restore the mail. Also, since my email reads from a corporate account that store all of my email for Webmail purposes, Outlook is now busily downloading duplicates of all my mail.

    Here’s hoping I live to see the day that Microsoft collapses under its own low regard for reliability and user experience.

  9. Jose Carlos said on January 26, 2010 at 3:09 pm

    Muito bom. Funcionou perfeitamente. Obrigado

  10. Jorge said on December 23, 2009 at 11:49 am

    Great Tool! But it scans for duplicates only withon the same folder. Does anyone knows of a freeware that scans between diferent folders? Thanks

  11. Mirza said on October 6, 2009 at 10:14 am

    Thanks a lot Martin you saved our life,



  12. Froebel said on July 23, 2009 at 9:06 pm

    It worked fine for mi also.
    Version installed: 1.4.2
    on Vista Home Premium and Outlook 2007 SP2.

  13. Jan Popovic said on January 25, 2009 at 2:36 pm

    ODIR works perfectly fine for me in the Outlook 2007 environment. Extremely useful tool solving a silly bug, which I would really expect Microsoft to have tested in the latest version of their email client tool.

  14. Michael said on December 23, 2008 at 7:07 am

    ODIR works just fine on XP Pro & Outlook 2007.
    What a relief, not having to weed out the duplicates of over 1400 mails that were re-downloaded from a POP account.

    Thanks for the article.

  15. Mulcherman said on May 2, 2008 at 8:30 am

    Installs and runs fine with Office 2007/Vista Home Premium. Just make sure that Vista and Office are fully updated with Service Packs and all “custom” updates. Re-start and run Disc Cleanup utility (in Accessories – System Tools) and all should work fine.

  16. Thalia said on March 15, 2008 at 6:09 am

    Duplicate emails: Ever since I subscribed to Verizon wireless sync for my cell phone with Vista-Office Outlook 2007, I get duplicate emails. The Verizon help line has really tried, but they cannot figure out the cause. My cell phone is an LG and the software for it is referred to as “BREW”. I wish I understood the POP stuff. Any suggestions? Thanks.

  17. Mike said on March 3, 2008 at 8:35 pm

    ODIR works great on Outlook 2007 and XP. It runs slower that other utilities that charge for their software, but I can live with the cost/inconvenience ratio. I imported a large inbox from Eudora which created duplicate contacts as well as all emails. All is good now! Thanks for the article.

  18. jjakober said on February 20, 2008 at 11:15 pm

    I just installed this on Vista/SP1 with Outlook 2007/SP1 and it works perfect.

    Great tool!

    Not sure why it works for me and not others, maybe the service packs?

  19. Augustine Vinh said on February 9, 2008 at 10:43 pm

    No luck with Vista and Outlook 2007. I have tried many times. I need help from anybody having similar problems and a solution. I have about 6 or 7 duplicates per entry.

  20. James Woo said on June 14, 2007 at 11:31 am

    I got a runtime error for Outlook 2003 under Vista. It runs fine on Outlook 2003 under WinXP.

  21. Robin said on May 29, 2007 at 12:49 am

    Installed in Outlook 2007 under WinXP and works fine. Not problem at all. The problem might be Vista, not Outlook.

  22. Amber said on May 22, 2007 at 7:18 pm

    Won’t even load in Outlook 2007 under Vista.
    At least, not for me. Under manage add-ins, it tells me that a runtime error occurred during the loading of the COM addin. I would be extatic if there was a solution to this.

    Microsoft’s KB article suggests that the solution is to sort/select/delete. Hmmm… with all the Google hits for “remove duplicate items from outlook” you would think they might eventually impliment this themselves. Of course, they are probably blissfully ignorant about any buzz on the net regarding missing features.

    They could hire me to surf for this info for them… hehheh

  23. Joel said on April 23, 2007 at 2:42 pm

    I appreciate the heads-up on crashing Outlook 2007, but if anyone has any suggestions other than “get over it”, I’d appreciate it. I use a palm pda and due to snafus in hotsyncing, I have 2-4 copies of nearly every contact in my phone book. This is a pain when I’m scrolling for them on my palm. I’ve also ended up with some duplicate tasks and appointments. So, if anyone knows of something that works, please let me know.

  24. TBIRD7777 said on April 19, 2007 at 4:52 am

    Don’t bother to download if you have Outlook 2007. With very few exceptions Outlook 2007 does NOT like Third Party Add-Ons and for most of the time does not even like Add-Ons from Microsoft. This particular “Add-On” will crash Outlook 2007 100% of the time……….live with a few dups………get over it!!!

  25. Rokomawh said on April 16, 2007 at 12:07 pm

    Thanks. I’ve found this article very useful.

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