[ietf-dkim] lets add one more shall we?
chl at clerew.man.ac.uk
Fri Jun 8 01:59:49 PDT 2007
On Thu, 07 Jun 2007 14:41:22 +0100, Hector Santos <hsantos at santronics.com>
> 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
Email: chl at clerew.man.ac.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
More information about the ietf-dkim