[Dovecot] Using Dovecot-auth to return error code 450 (or other 4xx) to Postfix when user is on vacation

[Joseba Torre]

> anyway if you use other vacation tecs, make sure allready flagged spam
> by i.e clamav, amavis, spamassassin etc in postfix stage is not handled
> by your vacation service , script etc.
> as far i remember i gave some patch to the postfixadmin vacation script
> doing exact this

If you're using any antispam soft that gives every mail a spam score 
(like spamassassin does), you can use a strong rule for vacation replies 
(like "only messages with a spam score under 5 are allowed, but only 
those under 3 may have a vacation reply").