On Thu, 07 Jun 2007 14:41:22 +0100, Hector Santos <hsantos(_at_)santronics(_dot_)com>
wrote:
Charles Lindsey wrote:
In other words, not all MX query gives you IP addresses to try.
So in that case, you can have an MX that directs you to the domain
nomail.invalid (which has no A record, of course) and that is the end
of the matter. What is wrong with that?
A change in long establish SMTP semantics and sending strategies.
No. Just a way to say this domain does not want to receive any email, even
though it has an A record. That MX should get cached (so no excessive load
on the authoritative server). And nomail.invalid should also get cached,
as a DNS failure, or so I have been informed, so no excessive load on the
root servers; a smart DNS resolver will already have built into it that
'invalid' is not even worth looking up. I proposed it as an alternative to
the suggested "MX .", which apparently had problems.
Each implementation may have their own set of wrappers, for example in
Wildcat! SMTP, if enabled by the sysop, failure to deliver after the X
number of retries may get the domain blacklisted. We also have a CBV
(SMTP callback) and NXDOMAIN failures promotes 45x responses. It works
like a GREYLIST hence bad systems don't try again, good systems do.
A domain which does not want to receive email should welcome such
blacklisting. Agreed it should be reviewed after some TTL.
--
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131
Web: http://www.cs.man.ac.uk/~chl
Email: chl(_at_)clerew(_dot_)man(_dot_)ac(_dot_)uk Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
PGP: 2C15F1A9 Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5
_______________________________________________
NOTE WELL: This list operates according to
http://mipassoc.org/dkim/ietf-list-rules.html