[Mimedefang] Soliciting opinions on filtering based on bad MX records

[Steffen Kaiser]

On Thu, 11 Sep 2003, Michael Sims wrote:

> (3) If the MX record is a hostname, I retrieve the A records for it.  If
> they don't exist, I return false.  If they do, I test each A record,
> returning true if any one of the records is "bogus", false otherwise.

To emulate the behaviour of sendmail in case multiple MX records do exist,
you should verify the "validity" of the retrieved information by
connecting to the machine. however, this will generate lot of fun, if
everybody on the net does that.

BTW: I was thinking about such stuff, too, when I saw my mail queue
overcrowded by DSN's to faked addresses _tempfailing_ because of using
such config, e.g. @localhost.com. -> MX: ghost.localhost.com. -> IP:
10.11.12.13 --> sendmail tries to connect some internal host and is
tempfailed.

Bye,

-- 
Steffen Kaiser