Fix Gmail IMAP slowing down Thunderbird or mails not arriving in a timely fashion

Martin Brinkmann
Sep 7, 2013
Updated • Jul 31, 2015
Email, Thunderbird

The Thunderbird email client had to take a back seat over at Mozilla when the organization decided to spend resources on other projects instead. While it is still maintained, for instance with regular security updates, there has not been any updates of note in recent time that added new features to the desktop email program.

Update: Mozilla changed the value of the preference described in the guide below to false. This means that it is no longer necessary to make the change manually. If Thunderbird is still slow on your end, try this fix.

If you have your Gmail email account linked in Thunderbird using IMAP, you may have noticed that emails do not arrive in a timely fashion anymore, that retrieving emails takes quite some time, and that it is slowing down the system in the process.

According to initial reports, users who make - heavy - use of labels are affected by this the most. The cause for the issue has been identified by Mozilla. According to a bug report, it is Google's recent introduction of CONDSTORE for all Gmail users that is causing the issues.

What it does?

The Conditional Store facility provides a protected update mechanism for message state information that can detect and resolve conflicts between multiple writing mail clients.

The solution itself is rather simple at this point in time. Disable CONDSTORE in Mozilla Thunderbird to resolve the issue. That's not optimal but users who experience slow downs or other Gmail related issues in Thunderbird when using IMAP may want to give this a try to see if it fixes the issues they experience.


To disable CONDSTORE do the following:

  1. Click on Tools > Options in the menu bar.
  2. Select Advanced > General and click on Config Editor here.
  3. Type condstore in the search box and wait until the results are filtered automatically.
  4. The only result is the mail.server.default.use_condstore preference.
  5. It has a boolean value set to true (which means it is enabled).
  6. To disable it, double-click the name. This should set it to false.

Sören notes that there is also an undocumented preference that you can use to disable CONDSTORE for individual mail servers.

Use mail.server.server*.use_condstore where * is the number of a mail server to disable CONDSTORE for that mail server only. You can display server numbers by clicking on Help > Troubleshooting Information. Here you see account IDs, and the number next to those IDs indicate the server number.

Mozilla plans to disable CONDSTORE by default for all users in the next update. While no final decision seems to have been made in this regard, it is the most likely cause of action considering that it is currently unclear how many users of the email client are affected by this.

Fix Gmail IMAP slowing down Thunderbird or mails not arriving in a timely fashion
Article Name
Fix Gmail IMAP slowing down Thunderbird or mails not arriving in a timely fashion
Find out how to fix Thunderbird slowing down when it is accessing Gmail contents over IMAP.

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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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