dovecot - Jan 2009 - Maildir++ quota: When is it recalculated?

We use Maildir++ quota, with the rules taken from our LDAP backend. We also
have an old expunge script that's not quota-aware; it removes old messages
from the maildir by simply deleting the files.

Sometimes, a mailbox is over quota before the script runs, but well under
quota after the old messages are deleted. This change does not seem to be
picked up, however: When I try to deliver a new message (using Dovecot's
deliver), the attempt fails with an "over quota" error.

I tried finding out from the source code whether this is intended behavior,
but unfortunately, I'm not enough of a programmer, so I have to ask here:
Should I be able to delete mails from a maildir, and expect the quota
plugin to notice the change?

We use Dovecot 1.1.8, by the way.

Ulrich

On Wed, 2009-01-14 at 14:30 +0100, Ulrich Zehl wrote:
> We use Maildir++ quota, with the rules taken from our LDAP backend. We also
> have an old expunge script that's not quota-aware; it removes old
messages
> from the maildir by simply deleting the files.
> 
> Sometimes, a mailbox is over quota before the script runs, but well under
> quota after the old messages are deleted. This change does not seem to be
> picked up, however: When I try to deliver a new message (using
Dovecot's
> deliver), the attempt fails with an "over quota" error.
> 
> I tried finding out from the source code whether this is intended behavior,
http://www.inter7.com/courierimap/README.maildirquota.html explains it
in "Calculating the quota for a Maildir++". Dovecot uses the same
method.
> but unfortunately, I'm not enough of a programmer, so I have to ask
here:
> Should I be able to delete mails from a maildir, and expect the quota
> plugin to notice the change?
I think it should notice most times, but not necessarily always. Can you
reproduce this with simple steps? Meaning that if maildirsize file is
either older than 15 minutes or longer than two lines, does Dovecot not
recalculate the quota when user is over quota?
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On Wed, Jan 14, 2009 at 10:18:30AM -0500, Timo Sirainen
wrote:
> > but unfortunately, I'm not enough of a programmer, so I have to
ask here:
> > Should I be able to delete mails from a maildir, and expect the quota
> > plugin to notice the change?
> 
> I think it should notice most times, but not necessarily always. Can you
> reproduce this with simple steps? Meaning that if maildirsize file is
> either older than 15 minutes or longer than two lines, does Dovecot not
> recalculate the quota when user is over quota?
Yes, I can. However, the user is, strictly speaking, not over quota, since
there are still a few bytes free. The new message would push it over quota,
though. Does this make a difference?

These are the steps I took, starting from a "fresh" account (one whose
home directory I deleted), and using swaks[0] to generate the mails. We use
Postfix to pipe the messages to deliver, and have set
quota_full_tempfail = yes.

1. Delete the user's home directory

2. Deliver 3 messages to the user, using

# swaks -f ulrich at topfen.net -t grmpfl at example.net -s localhost

3. maildirsize now shows:

# cat Maildir/maildirsize
2000S
0 0
510 1
510 1
510 1

4. Try to deliver a fourth message (also 510 bytes). As expected, it fails.

# tail -n 2 /var/log/mail.log
Jan 14 17:15:02 carolyn deliver(grmpfl at example.net):
msgid=<20090114161502.7F2AA1C104 at carolyn.beispiel.at>: save failed to
INBOX: Quota exceeded (mailbox for user is full)
Jan 14 17:15:02 carolyn postfix/pipe[8461]: 7F2AA1C104: to=<grmpfl at
example.net>, relay=dovecot, delay=0.18, delays=0.12/0.03/0/0.03, dsn=4.3.0,
status=deferred (temporary failure. Command output: Quota exceeded (mailbox for
user is full) )

5. Remove one of the files:

# rm Maildir/new/1231949258.M463705P8296.carolyn\,S\=510\,W\=524

6. Try to deliver the message again, and watch it fail again:

# postqueue -f
# tail -n 2 /var/log/mail.log
Jan 14 17:15:55 carolyn deliver(grmpfl at example.net):
msgid=<20090114155631.BCDB71C0DA at carolyn.beispiel.at>: save failed to
INBOX: Quota exceeded (mailbox for user is full)
Jan 14 17:15:55 carolyn postfix/pipe[8461]: BCDB71C0DA: to=<grmpfl at
example.net>, relay=dovecot, delay=1164, delays=1164/0.04/0/0.02, dsn=4.3.0,
status=deferred (temporary failure. Command output: Quota exceeded (mailbox for
user is full) )

7. Try ageing maildirsize and a new delivery:

# touch -t 01010101 Maildir/maildirsize
# postqueue -f
# tail -n 2 /var/log/mail.log
Jan 14 17:18:42 carolyn postfix/pipe[8553]: 7F2AA1C104: to=<grmpfl at
example.net>, relay=dovecot, delay=220, delays=220/0.05/0/0.03, dsn=4.3.0,
status=deferred (temporary failure. Command output: Quota
exceeded (mailbox for user is full) )
Jan 14 17:18:42 carolyn postfix/pipe[8554]: BCDB71C0DA: to=<grmpfl at
example.net>, relay=dovecot, delay=1331, delays=1331/0.01/0/0.03, dsn=4.3.0,
status=deferred (temporary failure. Command output: Quota exceeded (mailbox for
user is full) )

8. Try deleting maildirsize and a new delivery:

# rm Maildir/maildirsize
# tail -n 3 /var/log/mail.log
Jan 14 17:19:48 carolyn deliver(grmpfl at example.net):
msgid=<20090114161502.7F2AA1C104 at carolyn.beispiel.at>: saved mail to
INBOX
Jan 14 17:19:48 carolyn postfix/pipe[8553]: 7F2AA1C104: to=<grmpfl at
example.net>, relay=dovecot, delay=286, delays=286/0.04/0/0.13, dsn=2.0.0,
status=sent (delivered via dovecot service)
Jan 14 17:19:48 carolyn postfix/qmgr[3599]: 7F2AA1C104: removed


[0] http://jetmore.org/john/code/#swaks