🚀 go-pugleaf

stewart@wuzz.demon.co.uk (Stewart Brodie) wrote:
>Tim Illingworth <tim@smof.demon.co.uk> writes:
>>first line: the host that the message is to be delivered to
>
>>post.demon.co.uk

>Somebody else pointed out that the first line is looked up in the DNS
>for MX records first.
>
>If this is the case, then how does it know whether the first line is a
>mail domain or a smarthost?

It just assumes it's a mail domain.  KA9Q only tries the highest 
priority (lowest value) MX record and if connect() fails, falls back 
to a smart relay selected by IP address (A record, _not_ MX record)

>                             Taking post.demon.co.uk as an example, it
>has MX records pointing to a couple of the usual mail exchangers and
>then office.demon.net (IIRC, maybe it's one of the other machines).

The lowest MX record for post points to relay-3 AKA post [158.152.1.72]
so unless Demon are juggling the load between relays, KA9Q should send
it to post (the machine) first attempt.

Cheers, Graham.
-- 
----[ Graham E. Kinns ]----==========----< Graham@grempc.demon.co.uk >----