So we have a mail system built on postfix-courier-saslauthd with unix users and maildirs and TONS of shared folders. Both T'bird ( and Roundcube exhibits weird symptoms with subscriptions.

In Roundcube, if I go into Personal Settings -> Folders, 9 out of 10 times, it automatically subscribes me to ALL folders. Not cool.

In Thunderbird, when I open Subscribe..., then start going thru the folder structure (it loads them dynamically), it starts subscribing me to random folders, sometime an entire subfolder tree.

I'm starting to suspect that something weird is going on server-side. Anyone got any ideas? It's very, very annoying.

EDIT: ran T'bird in debug mode. I get tons of these messages: 1628149872[1e71f20]: considering playing queued url:imap://user@my.mail.server.address:143/unsubscribe>.shared/a/sub/folder

-1628149872[1e71f20]: creating protocol instance to play queued url:imap://user@my.mail.server.address:143/unsubscribe>.shared/a/sub/folder

-1628149872[1e71f20]: failed creating protocol instance to play queued url:imap://user@my.mail.server.address:143/unsubscribe>.shared/a/sub/folder


I recommend to consider using dovecot instead of courier-imap.

  • Well, maybe on the long term. How hard is to, say, migrate the whole damn thing? – KTamas Jun 8 '09 at 11:19
  • I think it is not that hard. It handles maildirs so this part is ok. You have to configure it anyways. I have one idea regarding the original question: you can try sniffing what commands these clients are issueing. If it is not their fault (you will see from the commands sent on the wire) then it is definitely a server issue. – cstamas Jun 8 '09 at 11:26
  • I'll second the recommendation to switch to dovecot, it performs much better on large mailboxes and requires fewer resources than Courier. IIRC, migration was not difficult, and there's even a Wiki page on doing it: wiki.dovecot.org/Migration/Courier – tomlogic Jun 10 '09 at 22:43

Needs a bit more detail.

Subscribes to only shared, only private, or both?

Most likely sounds like a bug in courier, but check the courierimapsubscribed file and see if there's anything strage there.

Update: Based on the courier docs: http://www.courier-mta.org/imap/README.sharedfolders.html

It seems like user subscriptions to shared folders depend on how they're implemented.

  • shared only, it seems. We don't use much private folders, but that worked so far I think. I'll check that file. – KTamas May 26 '09 at 8:31
  • Nope... nothing strange in courierimapsubscribed. But it only has the private folders. – KTamas May 26 '09 at 8:33
  • 1
    they are "Filesystem permissions-based shared folders". – KTamas May 27 '09 at 9:25

RoundCube should not automatically subscribe you to all folders. Can you tell me which version you are using? I'd help you get this sorted. Hopefully you are running one of the latest releases.

Btw, I am using courier-imap as well (with Postfix). And I personally am folder-crazy. And it all works for me.

[Disclaimer: I'm one of the developers of RoundCube.]



Maybe you're looking for some other solution as well: I have had best experience with Cyrus imap. More capabilities than courier and much much faster (and this is with a dozen users already).

  • Same question, how hard is to migrate? – KTamas Jun 8 '09 at 11:19
  • I've set up the new server (with help of my friend who knows postfix well), then migrated messages using perl script named imapsync. Apart from learning postfix and running imapsync several times it's been fairly simple. – slovon Jun 8 '09 at 14:07

I love RoundCube and use it with Gmail Apps, but it does seem to do some odd things with folders. I've had it created and copy folders too.

Waiting for a production release might be better.


In the IMAP protocol, the subscription bit is saved on the server side. I wonder if your IMAP server is saving that bit on the folder itself. If that is the case, then all of your users will be "subscribed" to the same folder.

How do you have your shared folders set up? If you just create symlinks from the shared folders into the user's maildir, you'll likely experience this problem.

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