[Dovecot] Postfix aliases with quota-status service
/dev/rob0
rob0 at gmx.co.uk
Tue Aug 6 21:49:57 EEST 2013
On Tue, Aug 06, 2013 at 09:27:20PM +0300, Timo Sirainen wrote:
> On 6.8.2013, at 20.57, Thomas Leuxner <tlx at leuxner.net> wrote:
> > * Timo Sirainen <tss at iki.fi> 2013.08.06 19:42:
> >
> >> The idea behind quota_grace is that the last mail would be
> >> allowed to take the user somewhat over quota (e.g. up to 109%
> >> quota usage). On the next mail delivery user is already over
> >> quota, so the size of the mail is irrelevant because a mail
> >> of any size will be rejected. The initial quota-status
> >> implementation didn't even support SIZE extension since I
> >> didn't remember it existed.
> >
> > I'm referring to the Postfix side _only_ or the initial SMTP
> > Handshake if you like. My point is that there is no safe way
> > to reject mails at this level *if* the remote server doesn't
> > play nice. I think this was the whole point of writing a
> > policy service for Postfix. I'm not *talking* about quotas
> > that will be handled by the delivery agents...
>
> Either you're still misunderstanding me, or vice versa. The quota
> rejections can be done complete in SMTP side even without SIZE:
Another way, in Postfix, is to wait for end-of-DATA. Regardless of
SIZE being given, at that point, the actual size is known.
Of course as Thomas would probably point out, such a rejection is
unsafe, because ANY overquota recipient would cause rejection for
EVERY recipient; SMTP cannot have per-recipient results except at
"RCPT TO:".
Personally, I'd much rather allow the last overquota mail, even in
cases where the user goes far over the quota. Apparently Thomas
intends to have a solid, inflexible quota.
In that case I'd suggest going for a lower quota and adding
quota_grace. Let quota_grace plus quota be the most you can tolerate
in your users' mailboxes.
> 1) quota at 99% :
>
> MAIL FROM:<sender at example.com>
> 250 2.1.0 Ok
> RCPT TO:<tss at dovecot.org>
> 250 2.1.0 Ok
> DATA
> ...
> .
> 250 2.0.0 Ok: queued as 12345
>
> 2) quota is now at 103% :
>
> MAIL FROM:<sender2 at example.com>
> 250 2.1.0 Ok
> RCPT TO:<tss at dovecot.org>
> 554 5.2.2 User is over quota
>
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