sane filesystem quotas with maildir
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From: Noah Sheppard on 17 Dec 2009 17:35 Postfix users, I am attempting to set up postfix such that using filesystem quotas on users' mail spaces (a directory whose subdirectories are maildirs). After RTF{manual, google, list archives}, I haven't been able to find any good way to do this. A problematic requirement is that we can't let the user go over their soft quota, because if they do and their grace runs out, they will be unable to free up space via IMAP, since common IMAP clients try to copy messages to Trash as part of the deletion process. I've thought through the following possibilities, with the given problems: 1-mailbox_size_limit: ineffective; I'm using maildir, and that's not filesystem-based anyway. 1-A milter/access policy which checks per recipient to make sure this message will not put them over quota: fail, we don't know the size of the message at the point in the SMTP exchange where we can reject individual users. 2-Same as (1) but assume that the message is message_size_limit large: annoying because it essentially makes an amount of the users's space unusable 2-A milter/access policy which checks after end of data to make sure this message won't put users over quota: fails because this would mean rejecting the message for all local recipients just because one was over quota. 3-Just setting quotas and letting procmail fail to deliver the message and generate a bounce message: fails because postfix keeps trying to deliver the message for a long time; we would like a relatively quick fail and notification. 4-Another item in our mailbox_command pipeline which checks the users' quota and rejects if the message would put them over it: kind of works, but there is no return code for the command to use to tell procmail that the delivery failed due to quota issues, causing a proper DSN 5.2.2 to be returned. Also, the bounce message this generates is a type of backscatter, though it may be unavoidable because of how the SMTP protocol works (recipients before message size). (4) seems to me to be the most promising, if there were a way to have my quota-checking script tell Postfix to send a 5.2.2 DSN. Has anybody else dealt with this and prevailed? Thanks much, -- Noah Sheppard Assistant Computer Resource Manager Taylor University CSE Department nsheppar(a)cse.taylor.edu
From: Wietse Venema on 17 Dec 2009 17:53 Noah Sheppard: > 3-Just setting quotas and letting procmail fail to deliver the message > and generate a bounce message: fails because postfix keeps trying to > deliver the message for a long time; we would like a relatively quick > fail and notification. procmail returns a TEMPORARY error condition to Postfix. Don't blame Postfix for procmail brain damage. Wietse
From: Noah Sheppard on 18 Dec 2009 09:51 On Thu, Dec 17, 2009 at 05:53:13PM -0500, Wietse Venema wrote: > Noah Sheppard: > > [..] postfix keeps trying to deliver the message for a long time > > procmail returns a TEMPORARY error condition to Postfix. > Don't blame Postfix for procmail brain damage. > Understood. Actually, this was our fault as we have the '-t' switch on our procmail command, so procmail exits with EX_TEMPFAIL rather than EX_CANTCREAT. As there is no exit code to tell postfix that delivery failed due to quota issues, is there any other way to insert a hook which checks and rejects on a per-user basis after we know the size of the message, and can tell postfix to return a 5.2.2 DSN? Thanks, -- Noah Sheppard Assistant Computer Resource Manager Taylor University CSE Department nsheppar(a)cse.taylor.edu
From: Wietse Venema on 18 Dec 2009 10:46 Noah Sheppard: > On Thu, Dec 17, 2009 at 05:53:13PM -0500, Wietse Venema wrote: > > Noah Sheppard: > > > [..] postfix keeps trying to deliver the message for a long time > > > > procmail returns a TEMPORARY error condition to Postfix. > > Don't blame Postfix for procmail brain damage. > > > > Understood. Actually, this was our fault as we have the '-t' switch on > our procmail command, so procmail exits with EX_TEMPFAIL rather than > EX_CANTCREAT. > > As there is no exit code to tell postfix that delivery failed due to > quota issues, is there any other way to insert a hook which checks and > rejects on a per-user basis after we know the size of the message, and > can tell postfix to return a 5.2.2 DSN? With the pipe-to-command/exit-status protocol, the only way to flag an hard error is by exiting with a status that reports a hard error, or by sending something to stdout that begins with a 5.2.2 status code. man 8 pipe Wietse
From: Michal Kurka on 18 Dec 2009 11:00
Dne 18.12.2009 v 10:46 Wietse Venema napsal(a): > > As there is no exit code to tell postfix that delivery failed due to > > quota issues, is there any other way to insert a hook which checks and > > rejects on a per-user basis after we know the size of the message, and > > can tell postfix to return a 5.2.2 DSN? > > With the pipe-to-command/exit-status protocol, the only way to > flag an hard error is by exiting with a status that reports a > hard error, or by sending something to stdout that begins with > a 5.2.2 status code. I think, if command from 'pipe' exit with error, then a mail remains in mail queue on local MTA. So there is no chance send 4xx or 5xx SMTP-code to sender MTA, because SMTP-communication with him is closed already. -- Michal Kurka - Mysak sluzby spojene s operacnim systemem Linux |