[Dovecot] Configuration of LMTP Reject Code

[Petter Urkedal]

On 2011-02-22, Timo Sirainen wrote:
> On Mon, 2011-02-21 at 11:05 +0100, Petter Urkedal wrote:
> > Is it possible to change the reject codes from the Dovecot LMTP agent?
> > In particular I would like to change the "550 5.1.1 <...> User doesn't
> > exist." to a temporary failure, since we already validate email
> > addresses on the mail front-end, and such errors are most likely due to
> > a temporary glitch in the user database lookup.
> 
> What userdb are you using? Temporary userdb lookup glitches should cause
> Dovecot to return a temporary error failure, not "user doesn't exist"..

We are using auth-system.conf.ext with

    passdb {
      driver = pam
    }

    userdb {
      driver = passwd
      args = home=/srv/mail/nbi.ku.dk/%1n/%n mail=maildir:~/Maildir
    }

We also have a post-login script which may override MAIL if the mail
directory does not exist.  This is on Red Hat 6 with the new sssd-based
user database and authentication.

We only have two rejects of this type, 9 s apart, since we switched to
the new mail server a week ago, so it's a rare event.

> > We use Postfix on the front-end, which is very configurable in this
> > respect.  I don't see a way to override the error code from LMTP,
> > though, but suggestions are welcome.
> 
> I don't really like adding settings that have very few users..

I understand, it's really a workaround.  A global directive to turn all
permanent errors into temporary ones, would do as well, since any error
from LMTP is a potential issue we want to know about.  I'm not sure
whether that's any nicer from your point of view.