From: Anthony Howe
Date: 2007-01-11 13:27:54 -0500
Subject: Re: single MX resolves to multiple hosts?
More information..: http://www.milter.info/#Support
Grant Taylor wrote:
> Ben Spencer wrote:
>> Milter-spiff failed the related email message. I suspect it is because
>> the connecting mail server was 220.127.116.11 and milter-spiff's lookups
>> returned 18.104.22.168.
> I have no comment on the operation of milter-spiff in this situation as
> I don't have enough information. However if this is indeed the case,
> (milter-spiff not properly handling multiple IP addresses for an MX)
> this is a bug that should be addressed and I'm sure that Anthony would
> have something to say.
There are two libsnert trouble tickets for this issue already.
Libsnert's DNS client code will fetch an MX record list and only use the
first one found if multihome. Generally this is sufficent for what is
was originally written for, milter-sender, since if you have two or more
MX entries (which is recommended Best Current Practice) and each
multihomed, then milter-sender would try each of the MX in turn upto the
This technique falls down for milter-sender in the case of only one MX
record, which is a bad idea already, that is multihomed.
RFC 2821 section 5. Address Resolution and Mail Handling talks about
multihomed MX records and in my mind leaves some wiggle room as to
However, the Dns.c fails to address the needs of milter-spiff and others
that need support for multihomed MX records
In the trouble tickets concerning this issue, I've conceded that missing
support for multihomed MX records is a bug, but it requires a major
change / rewrite to the Dns.c code, which will NOT appear in
libsnert/1.63 (unelss I find a nice simple hack) when I'm already 4
months overdue with the next round of updates, which already very extensive.
Anthony C Howe Skype: SirWumpus SnertSoft
+33 6 11 89 73 78 AIM: SirWumpus Sendmail Milter Solutions
http://www.snert.com/ ICQ: 7116561
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