Using Thunderbird's New Filelink Feature For Large File Attachments

Martin Brinkmann
Apr 27, 2012
Email, Thunderbird

If you are running the latest Thunderbird Beta, or one of the experimental versions of the desktop messaging client, then you may be interested that the new Filelink feature has been integrated into the version of the software. If you follow the news posted here on this site, you know that Mozilla Messaging announced plans a while ago to integrate an option to include file hosting support in Thunderbird.

This works similar to Hotmail's feature where large attachments can be hosted on SkyDrive instead. This has several positive effects:

  • Emails have a low size, and can be retrieved faster
  • Emails won't bounce because of attachment limitations
  • The recipient can decided whether to download the attachment, or not.

When you add a large attachment to a Thunderbird email that you are currently writing, you will see a notification suggesting to use the Filelink feature of the email client instead.

thunderbird large files

You can click on the learn more link for information about the feature, on link to use the new feature, or ignore to send the email with attachments the conventional way.

It allows you to upload attachments directly to an online storage service and then replaces the attachment in the message with a link. The recipient clicks the link to download the attachment. As additional benefits, sending and receiving large files is much faster and you will save disk space, both in therecipient's inbox and in your Sent folder.

When you click on the Link button you will notice that a Filelink setup window opens. Here you need to select the online storage provider that you want to use to host your attachments on. The beta version of Thunderbird supports Dropbox and YouSendIt.

thunderbird filelink dropbox yousendit

If you are using YouSendIt, you need to enter the account username and password of a YouSendIt account. You can set up an account with a click on the button in the configuration window.

Dropbox users need to authorize Thunderbird as well before they can use the cloud hosting and synchronization service to store email attachments online.

Once you have setup an account, you will notice a message stating that the file is being linked, and that it will appear in the body (as a link) when the upload is done.

email attachment

Once all files have been uploaded to the select file hosting service, you will notice that links have been added to the email body.

thunderbird attachment link

The recipient sees pretty much the same message, but with an added plain text link below the file link that you see on the screenshot above. Note the ad for Thunderbird that is displayed beneath the file link, and that you can remove it before sending the message to the recipients of it.

Thunderbird remembers the hosting service that you are using, and will use it automatically the next time you make use of the Filelink option in the email client.  A new outgoing attachment option has been added to the options of Thunderbird to manage the online hosting options.

file sharing thunderbird

Here it is possible to define the attachment threshold when sending large files, and to remove services that you have previously configured in the email client.


You will lose some control over the attachment if you select to use the Filelink feature. It is therefor suggested to use encryption for important attachments, to avoid them being read by third parties that are not authorized by you or the owner.

Another issue is that Thunderbird does not remember file links, which means that you can't easily use the links in additional emails. While you could copy and paste the link from previous messages, it does not seem like the best option, as Thunderbird could use hashes for instance to check whether links have been created before. Also, it would give Thunderbird users more control and an overview of the files they have uploaded this way to the file hosting services.

Filelink is currently integrated into the latest beta version of Thunderbird, which means that stable channel users will have access to it in about six weeks' time.


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  1. JMGG said on January 19, 2012 at 8:25 am

    You said that Outlook isn’t your main email client, so which is your main one?

    1. BalaC said on January 19, 2012 at 9:42 am

      I think its thunderbird

    2. Martin Brinkmann said on January 19, 2012 at 10:15 am

      It is Mozilla Thunderbird.

  2. Salaam said on September 24, 2012 at 9:52 pm

    Awesome! This actually solved my problem… what a stupid bug.

  3. Claud said on December 19, 2012 at 2:08 am

    If this is the same bug that I’ve encountered, there may be another fix: (1) hover over open Outlook item in Taskbar, cursor up to hover over Outlook window item, and right-click; (2) this should give you Restore / Move / Size / Minimize / Maximize — choose Move or Size; (3) use your cursor keys, going arbitrarily N/S/E/W, to try to move or size the Outlook window back into view. Basically, the app behaves as though it were open in a 0x0 window, or at a location that’s offscreen, and this will frequently work to resize and/or move the window. Don’t forget to close while resized/moved, so that Outlook remembers the size/position for next time.

    1. Lynda said on February 12, 2013 at 3:37 pm

      THANK YOU Claude!!! I could get the main window to launch but could not get any other message window to show on the desktop. You are my hero!!!!

    2. Chad said on November 20, 2018 at 4:24 pm

      Solved my issue! 6 years later and this is still problem…

    3. Ivan X said on January 21, 2021 at 4:50 pm

      Fantastic. Thank you. Size did the trick.

  4. Andrew said on October 26, 2013 at 7:06 am

    This solved my Outlook problem, too. Thank you. :)

  5. Charles said on December 7, 2013 at 7:23 pm

    Thank you so much, this started happening to me today and was causing big problems. You are a life saver, I hope I can help you in some way some day.

  6. garth said on November 7, 2014 at 7:13 pm

    You are a god – thank you!

  7. Faisal said on February 9, 2015 at 10:09 am

    thanks a lot…. work like charm.. :-)

  8. Simon said on March 24, 2015 at 11:36 pm

    Yah…thanks Claude. I’ve been having the same problem and tried all the suggestions…your solution was the answer. It had resized itself to a 0/0 box. Cheers

  9. Olu said on April 14, 2015 at 1:35 pm

    Excellent post. This had me baffled even trying to accurately describe the problem. This fixed it for me.
    Thank you

  10. Coenig said on July 23, 2015 at 7:36 am

    Thanks a lot for the article. Don’t know why it happenend, don’t know how it got fixed, but it was really annoying and now it works :-)

  11. Fali said on January 20, 2016 at 4:19 pm

    Thanks a lot. I was facing this issue from past 3 week. I tried everything but no resolution. The issue was happening intermittently and mainly when I was changing the display of screen ( as i use 2 monitors). The only option i had was to do system restore. But thanks to you.

    1. MIki said on January 10, 2019 at 11:54 am

      I’ve been tried to sole this problem for 12hours. Your comment about changing the display of screen helped me a lot!! Thanks!!

  12. Christina said on January 20, 2016 at 6:14 pm

    Thank you…don’t know why this happened but your instructions helped me fix it. Running Windows 10 and office pro 2007

  13. Oz said on July 22, 2016 at 3:20 pm

    Great tip! Thanks!

  14. Tracy said on September 1, 2016 at 4:48 pm

    Worked for me, too – thank you!!!

  15. shawn said on September 9, 2016 at 10:25 am

    It’s Worked for me, too
    thank you very much!

  16. Jari said on October 31, 2016 at 11:53 am

    I had a similar issue with Outlook 2013 on Windows 10 and this helped me to fix it. Thank you very much!

  17. Michel H said on November 30, 2016 at 11:08 pm

    Thank you so much. Solved!
    Considering you published this in 2012, incredible not been debugged by Microsoft.
    Thank you again. M

  18. Ziad Bitar said on January 9, 2017 at 2:00 am

    This problem was faced by only one user logging to TS 2008 r2 using outlook 2010.The issue was resolved.


  19. Anonymous said on February 15, 2017 at 5:24 pm

    Great tip. Thank you!!!! If it helps, I had to use the Control Key and the arrow keys at the same time to bring my window back into view. Worked like a charm.

  20. Rochelle said on March 6, 2017 at 11:59 am

    Thank you, this worked !!!!

  21. anom1234 said on May 20, 2018 at 11:20 pm

    Man, you are a fucking god. Thanks a lot, what an annoying bug!!

  22. JC said on October 12, 2020 at 2:14 pm

    Awesome, this post solved the issue. Many thanks!

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