Re: Advanced tricks I use to get rid of spam using MX 4xx

["Jason Frisvold" <xenophage0@gmail.com>]

On 11/27/06, Marc Perkel <marc@perkel.com> wrote:
>  No - on my system a 4xx error only means that that particular server isn't
> ready. It means try the other servers or come back later. It certianly dos
> not mean that all the servers aren't ready. That's what I use EXIM and not
> Qmail. All other MTAs except Qmail behave this way. it's what the spec says.
> Qmail does it wrong.
Hrm..  I find this interesting and slightly disturbing.  Can you
please provide the spec and highlight the passage which identifies
this behavior as correct?

I'm not sure I like the idea of a mail server immediately trying
another MX if the initial one it contacted was busy.  This just
creates additional load on the other MXs and can cause additional
meltdown.  I believe the "correct" way for this to work is to queue
the message when a 4XX is received and retry later.  When later
arrives, the MX lookup is repeated and at that point it's possible
that an alternative server is chosen.

--
Jason 'XenoPhage' Frisvold
XenoPhage0@gmail.com