🚀 go-pugleaf

In article <878846387snz@grempc.demon.co.uk> I wrote:

>A diff against the DIS 2.16 source to fix the major problem
>is attached below which will result in resolve_mx() failing (returning
>0) if no MX records exist (or MX records exist with no resolvable
>hostnames :( ); the code in smtpcli.c, mailroute() performs the MX to
>A record fallback behaviour required by the STD.

Further to that, having had chance to check that the resolver's
cacheing of negative responses meets RFC1034, RFC1123 and subsequent
clarifications, I now have a revised, tested patch to meet RFC974 (and
also the current DRUMS draft).  This ensures that the A record is
never tried unless an authoritative negative response for the MX
record is received so e.g. mail2news@news.demon.co.uk would never be
sent to a newsserver should the MX lookup timeout for any reason.

I can post the diffs against the current DIS source if there's any
interest ...

(I'm also open to any input on whether it's worth modifying the code
to cache negative responses in domain.txt - they aren't at present).

Cheers, Graham.
-- 
Graham E. Kinns
Graham@grempc.demon.co.uk