Re: SMTP traffic control

Paul Smith <paul(_at_)pscs(_dot_)co(_dot_)uk> writes:

> (I suspect the server is giving a 4yz because it is doing call-forward
> testing whether the remote recipient exists, and gets no response either
> from a DNS server or mail server for that address)
I believe Postfix returns those sorts of 4yx errors when configured to use
LDAP-based alias lookup and the LDAP server is not responding.

-- 
Russ Allbery (rra(_at_)stanford(_dot_)edu)             
<http://www.eyrie.org/~eagle/>