Question about cyrus quotas - how it behaves

David R Bosso dbosso at
Wed May 4 18:58:18 EDT 2005

--On May 4, 2005 4:19:51 PM -0600 Sun Advocate Webmaster 
<webmaster at> wrote:

> Just a question for all of you about quotas on cyrus imap.
> As far as I see, there is no "grace" quota or warning system. Users not
> watching the size of their mailboxes won't know they're near full until
> they're actually full. Is this the case?

Check out quotawarn: and quotawarnkb: in man imapd.conf.  They result in 
IMAP ALERT messages being generated.

> Lets say a user has a 20 MB quota on their mailbox. Lets say it currently
> sits at 19 MB (usage). Then, assume postfix hands over a 1.5 MB email
> (uncommon, but if there are attachments...). Does Cyrus accept this
> message but no further emails, or does it flat-out deny it?

The former.  Mail isn't rejected until the box is over quota.

> If it does deny this 1.5 MB email, does it accept a 3k email from postfix
> that arrives moments later?
> I assume once the quota has been exceeded, users won't be able to receive
> new email until they delete old ones. Is the quota restriction/ban
> "lifted" immediately after the offending user deletes enough of their
> emails?

Yep.  It's also a non-fatal delivery failure, at least on my setup.  So 
mail will continue to be retried until a hard fail, 5 days or so.

> Most of my IMAP users (local subnet) will be using Mozilla Thunderbird.
> The remaining users will be mostly POP on Outlook (remote users).

POP is a problem because it doesn't provide any feedback like IMAP ALERT.

In addition to the IMAP ALERTs provided by the quotawarn settings, we do a 
weekly cron script that sends an email to users approaching quota.


David R Bosso <dbosso at>
Systems & Network Manager, Letters and Science IT
UC Santa Barbara - 1054 North Hall 805 451-7160

Cyrus Home Page:
Cyrus Wiki/FAQ:
List Archives/Info:

More information about the Info-cyrus mailing list