[Dovecot] disabling mail delivery for a user

[Frank Cusack]

On February 2, 2010 9:57:12 AM +0100 Steffen Kaiser 
<skdovecot at smail.inf.fh-brs.de> wrote:
> IMHO:
> If you want to avoid backscatter, you must disable the user in the MTA,
> in order to reject the message during "rcpt to" command or at least in
> DATA.

I don't care about backscatter.  There's no reason anyone should see
significant backscatter these days; it's pretty much a solved problem.

(watermark all outgoing email and look for that watermark on DSN reports)

In any event, for this specific case I do already reject the user "at
the gates".  But I want to reject internal email for folks that don't
know that user account has gone away.  I prefer not to do it in the MTA
so as to keep the MTA as free from this type of configuration that
lingers for years and makes future migrations difficult.

-frank