Thunderbird and gmail aren't exactly the best of friends. Gmail's labels mean that Thunderbird often downloads multiple copies of a single mail. Anything tagged in gmail will appear in a folder related to that tag, the "all mail" folder, and possibly the "inbox" and "sent mail" folders too. Thus a mail with multiple tags could potentially be stored more than four times in a local Thunderbird cache. This can make searching difficult, and is obviously wasteful of disk space.

The best solution I have come up with is as follows. Operate a zero inbox policy (i.e. use the inbox for processing live mail only and archive everything else) which eliminates an extra copy in the inbox. Secondly, configure Thunderbird not to sync the "Sent Mail" folder - this is a bit of a pain, since I actually find it quite useful to be able to look through just the mails I've sent, but a search can duplicate this functionality. In this way, most of the duplicates are removed, and only mail with tags is stored locally more than once.

Ideally, however, I'd only like one copy of each mail to be stored locally. I am surprised Thunderbird doesn't store mail by some sort of hashing algorithm to prevent precisely this problem - but it wouldn't be compatible with the way the folders are mirrored in a local directory structure, I suppose.

Can anyone think of a better way to get Thunderbird to cache a Google mail account locally efficiently.

  • 2
    This is not at all a problem between Thunderbird and gmail. It's a problem between IMAP and gmail. IMAP has no concept of tags and it has no concept of the same message existing in multiple folders. Google has no way of communicating to Thunderbird (or any other IMAP client) the fact that two messages in two folders are in fact the same message. There are only two ways around that: use a different protocol than IMAP that supports this, or use an IMAP protocol extension that supports this (if there existed one).
    – Celada
    Jun 4, 2013 at 1:10
  • Please could you explain whay you call "zero inbox policy" I mean how are your settings in Thunderbird?
    – sebelk
    Mar 11, 2014 at 16:58
  • 1
    A 'zero inbox' policy is nothing more nor less than never leaving messages in your inbox. So normally your inbox is empty. Oct 2, 2014 at 12:57

5 Answers 5


There is no need for a workaround anymore. Thunderbird version 38 and newer support GMail labels. According to the documentation an e-mail is downloaded only once:

Note that a message can have multiple labels (for instance, "Personal", "Travel", "All Mail" and "Starred"). In this case, a single copy of this message will be downloaded, but it will be displayed in all the corresponding Thunderbird folders.

  • This is excellent news. Will it clean up old downloaded mails though?
    – Christi
    Dec 5, 2015 at 9:57
  • @Christi I'm sorry but I don't know :( Dec 5, 2015 at 15:42

For the record, IMAP does support tags (they're called keywords and implemented as flags), and Mozilla Thunderbird and SeaMonkey use IMAP tags.

See this discussion from 2006 with Mark Crispin.


For support of Gmail labels in Thunderbird install the development version of the Gmail Buttons Add-on.

NOTE: You must download the installer from the Development Channel at the bottom of the Add-on web page and install it via Tools>Add-ons>Wrench menu>Install Add-on From File... after downloading!

The regular installation will not provide working Gmail labels on top of any mail message.

Also note that this will not provide unified handling of Thunderbird labels and Gmail labels. Also, Gmail labels won't show up in the Tag column of your message list. But having labels on top of any email message is indeed a nice thing! -- Attached labels can be removed (through an x next to the label, as in Gmail), and labels are added by moving them into one of the IMAP folders (I've not found an attach label-only functionality yet, hmm). Neat!

P.S.: Unfortunately, with today's update to version 31.0 this extension has become incompatible with Thunderbird.


One can hide any mail account Labels from IMAP in Settings - Labels after login to the Gmail account with a web browser. This way Thunderbird will sync only Labels (folders) Shown in IMAP by Gmail servers.


Celada is correct -- IMAP is the problem and not Thunderbird. It doesn't support gmail's added features like tags.

What you can do is set the "tag" folders in your Thunderbird client to only download the headers instead of the full message. That way when you search it won't have the opportunity of searching through the body of those duplicate emails. Hardly a great solution, but at least a mini solution to the specific problem you are seeing.

This post has some more helpful suggestions: https://superuser.com/a/48602/128630

I think this question should just be merged with that one actually.

  • Given that the linked to question is primarily about tags and this one is about storage, I don't think it is a duplicate, let alone an exact duplicate.
    – Mark Booth
    Jun 4, 2013 at 8:59
  • I agree - the two questions are only tangentially related and merging would be inappropriate in this case.
    – Christi
    Jun 4, 2013 at 9:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.