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Open winmail.dat files on a Mac

TNEF's Enough Mac ApplicationIt’s bound to happen on a Mac. Someone will send you an email and tell you to check out the attachment. However, the only thing attached is a winmail.dat file. Good news though, you can open that file.

is a little freeware application that can open winmail.dat files and extract the attachment that is inside. It works quite nice and is free.

Winmail.dat files come from those Microsoft Outlook or Exchange programs and are some sort of archive method. Somewhere in outlook they get automatically created when forwarding email messages and Mac users have long wondered what they are and how to open them. Of course Windows users have no idea what they are either and think it’s all the receivers issue when we say we never got an attachment. Trust me, it’s easier to get TNEF’s Enough than try and work with a Windows user to get their email to stop sending winmail.dat files.

Do you need more of an explanation on what winmail.dat files are?

The file is a rich text (or MAPI) message that is sent from Outlook to Exchange. When Exchange sends the message to an outside server it writes the MAPI message as a MIME attachment. The unfortunate side effect of this plan is if the Outlook user has someone in their address book as a person who can receive “Rich Text” then the user will receive the TNEF file whether the user uses Outlook or not.

Check out .

72 Responses

  1. Robin Ray says:

    Thanks a million! I’ve had numerous requests from puzzled Mac users about winmail.dat files, and TNEF’s enough worked great. Keep up the good work!

    • Ray says:

      I use Entourage on my Mac also. TNEF only works sometimes. Most others, when I use it, all I get is “attributes”, no translated document.

    • mark says:

      I made some video on an ipod and could not download it to a mac. I then saw that the files were .dat and so I saved them onto the desk top.

      I downloaded TNEF, but I cant open TNEF and I still cant open the .dat files.

      Can anyone help?


      • Glen says:

        Place the downloaded TNEF’s Enough file into your applications folder. When you are ready to open a winmail.dat file, or similar, you’ll be ask to select the program to open it with. Select TNEF’s Enough. When you the image files appear within the window, simply open them or save them to a location on your computer. Hope this helps.

    • Ruth says:

      Oh WOW!! I love it when I research a puzzling situation and find the answer! That was easy!!
      Thank you sooooo much!!!

  2. Denis says:

    TNEF’s Enough doesn’t woprk for me. I am using Entourage 2004.

  3. Thomas says:

    The email client doesn’t matter. If there is anything in the winmail.dat file, TNEF should be ale to extract it. Save it to your desktop and open it from within TNEF.

  4. Genius. Thank you.

  5. tomek says:

    thank you! 🙂

  6. Mr. C says:

    Thank you, very helpful tip!
    Many others comments just play with tons of useless words about .dat files this post goes straight to the point and works fine!!!

  7. Thomas says:

    Glad you like it Mr. C. 🙂

  8. jimslinux says:

    I’ve used TNEF on this mac before, worked great. I however did a fresh install of leopard and reinstalled TNEF and it opens .dat’s in a blank page. I tried opening older saved .dat’s that I have opened successfully before and still a blank page.

  9. jimslinux says:

    I found that the preferences needed to be set up and all is well now. I think that TNEF should be integrated into OSX to work within the preview option to open the files in preview. Newer KDE based distros. open the .dat file in miniature when hovered by the cursor, the clicking it opens in a separate window. Thanks for a good product that works well.

  10. ejn says:

    Thanks!! Worked great for me, saved a lot of hassle.

  11. thx a lot – great help for us all.
    we would like to honour the work on TNEF in our NUTCASE currency – a Nutcase helmet. Please contact MICHAL (yes, without e) from the Nutcase Europe team.



  12. Christopher says:

    You can also try out OMiC, a Apple Mail Plug-in which process winmail.dat files in Mail.

    OMiC also support nested messages, VCF, ICS in winmail.dat files which TNEF’ Enough can’t export, and also handle long filename better.

  13. Tadd Peake says:

    What an elegant solution to a messy problem. Thank you very much.

  14. Frank Roberts says:

    Wow, thanks. So as a new MAC user, what to do, add Microsoft XP professional for MAC, or continue adding work-arounds? What to do?

  15. M Clarke says:

    Thanks! I always though that this winmail.dat thing was some bogus attachment. Now I see it is legit thanks to your suggested TNEF solution. I appreciate you taking the time to post answers for seekers like myself.

  16. Patricia says:

    I downloaded the TNEF, but when I click open on the attachment, there is nothing there. I don’t know if it is because my attachment is bogus or because I am doing something wrong. please help!

  17. Thomas says:

    To use TNEF drag the winmail.dat file on TNEF it’ll then show you what’s inside. Sometimes there are files, other times there is nothing.

  18. Andy says:

    Took me a while to get round to googling this irritating problem but now there’s a neat and efficient solution to all those winmail.dat files. Great ! Thanks.

  19. Chris says:

    You are a God – instead of trying to explain it to my boss I can just fix it – THANKS

  20. Guy says:

    Thank you! I got a winmail.dat file from a new client and was at a loss. You’ve saved my day.

  21. Doug mitchell says:

    had no problem opening on my pc lap top,

  22. Art says:

    Many thanks for this very useful app, now I don’t have to reply to the sender asking for them to send it again – they never understand what the problem is!

  23. Alex says:

    thank you i had to help a pc guy who was unable to open a file.
    i noticed that if i change name before saving the file get weird..

    lovre from Italy


  24. Pauline says:

    Thank you so much for this! Works perfectly and totally solves the issue 🙂

  25. Michael says:

    Thank you very, very much. Nearly lost my customer.

  26. Paul says:

    I hate it when .DAT happens.

  27. BG says:

    Thank you! «TNEF’s Enough» VERSION 2.2 works fine with SnowLeopard Mac OS 10.6.3
    After downloading «TNEF’s Enough» you must define the application’s prefences. Once in the prefences menu, select the way you whant it to work (Drag & drop or Application opened) and configure how it will process your .dat file.

    When using the application it will open a window titled «winmail.dat» and you will see the imbeded files. If there is none, your winmail.dat file is mostlikely corrupted. Ask the sender to resend by creating a new attachment in the email.

  28. Fatima says:

    I must have missed something because for me TNEF’s Enough is not enough. I downloaded the application and it does not do a thing. BG, I can’t set any preferences because none are presented. Dragging my winmail file to the application, Thomas, produces no result.

    It is somewhat frustrating to find so many of you raving about something which is failing miserably for me, and I am left feeling rather suspicious.

    • Thomas says:

      See now that’s what I’ve seen under 10.6 as well, but was excited to hear it got updated. Maybe it hasn’t. I don’t get many winmail.dat files anymore so I’m not sure if it works or not.

  29. Insa says:

    Very nice solution, Thanks! I did almost get in trouble with my boss when I told him I could not open his attachement 🙂

  30. Robert says:
    when You download this than eliminate Your problems with .dat file.

  31. Maria says:

    my mother thinks it’s too complicated. What can I do to make it simpler???

  32. Svetoslav Boiadjiev says:

    You could check “Klammer”. There are Mac and iOS versions, and covers winmail.dat, EML an .MSG files. Could be found at the AppStore.

  33. Terry says:

    I would love to find a program that works. This is NOT working. What am I doing wrong?

  34. La La says:

    I downloaded the correct version, read your instructions and it WORKED LIKE A CHARM! THANK YOU SO MUCH…YOU HAVE MADE MY LIFE COMPLETE. Just kidding, but thanks anyway!

  35. martin says:

    if you get the sender to go into there contact list and right click on your email address select outlook properties and then drop down the selections on the “internet format”, select “let outlook dicide the best sending format”. this will fix the senders problem when sending to that mac. unfortunately this has to be done for every address that is a mac.

  36. TOTO says:

    OK I’m one of the few that this wonderful ‘application’? is not working for .I have MAC OSX 10.5.8
    and I have the correct version of TNEF,but when I drag the winmail.dat attachment into the TNEF on the dashboard all I get is a small window with Embedded/Attributes at the top ,but blank text.
    I know the file is not corrupt because it opened with letter opener(now expired)
    Any suggestions?

  37. Jay BEE says:

    WoW this did work

  38. lone greve says:

    I think I have tried everything, but I still can’t open winmail.dat. Does anyone have a solution when you use Entourage as mailsystem and has Lion?

  39. John Scott says:

    This has cracked the problem completely. Thank you so much. The company IT specialists kept ignoring the problem and clearly thought it was just because I was an arrogant MAC user. I may be but that was not the reason for me being unable to see these attachments. Great work.

  40. Vince says:

    Works great . Thanks .

  41. eventbureau says:

    Just perfect – the problem with the winmail.dat are now fixed.
    Thanks a lot. Cheers eventbureau

  42. Dan says:

    Does “Enough” work on Thunderbird?

  43. Mike says:

    Ill admit I didn’t read all of the responses but the easiest solution I found is to just check my email in a web browser. Then the attachment comes through fine.

  44. Patrick says:

    Right on! TNEF did the trick.

  45. Rikki says:

    this is awesome! thanks for the info..

  46. darrel says:

    i’m getting a different issue. someone sent me a “FWD” to one of my emails and it came back with a “winmail.dat attachment. i just double clicked the attach and voila! i have complete access to my computer! the attach will plug me into my desktop, Iphoto etc. where did the sender get that attach?? darrel

  47. i am unable to open Winmaill.dat files even after downloading TNEF’s Enough.

  48. Darcy says:

    I downloaded TNEF – and was able to open the .dat file BUT it only gave me the body of the email and that there were 3 attachments and I couldn’t open those.

    Now what?

    • alhammer says:

      I have TNEF Enough and it does not work, although it used to before I upgraded to OS 10.7. I set preferences and followed them but nothing.

  49. Worked fantastically… and lo, there was a hidden pdf. Saved the expense of getting a priest in to do an exorcism.

  50. Sharon says:

    Thank you so much! Just downloaded it and worked like a charm. Donated $10 to TNEF’s Enough, too, to show my appreciation. Thanks again!

  51. Tiffany says:

    DIDN’T WORK FOR ME!! ?? Bummer, any ideas of where to go now? Files are scan’s I believe…. from a PC I’m on Mac, obviously.

    • tony says:

      TNEF’s Enough didn’t work for me either,but I managed to find another application called
      tnefDD,which did the trick…try that

  52. red says:

    Thanks heaps. $5 heading your way.

  53. Daniel says:

    I just started using Express Invoice and find that when I try to back it up my invoices are saved as .dat files. Not being able to open them, I downloaded TNEF’s Enough, but when using it to try to open the files get a message that they can’t be opened because they’re not TNEF files. This is all very confusing. I’m using OS X 10.7.5 with Office. Any suggestions?

  54. Lynnj says:

    Thank you so much for this – I’ve never been able yo open these stupid things on a PC let alone a Mac (and I’ll subscribe to you too 🙂 )

  55. MissAl says:

    I just changed the extension (in this case) to .jpg & was able to open them (TNEF didn’t work for me on latest Mac)

  56. Jimmy says:

    Good sharing! And my enolsoft winmail viewer also works like a charm on my iMac.

  57. Jeanie says:

    Awesome! Works perfectly, thank you!

  1. 3/17/2008

    […] so much to Twister Mc for the great […]

  2. 1/4/2010

    […] that took only a few minutes to write up and was actually from 2005! It’s a post about how to open winmail.dat files on a Mac. This is proof that writing a blog post shouldn’t take hours, doesn’t need a ton of […]

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