questionable email filtering policies?

Florian Weimer fweimer at
Fri Jul 24 13:39:15 UTC 2009

* Chris Hills:

> On the topic of mail rejection I have come across a few sites that
> reject mail, even to [email protected], from domains that have one or more
> ipv6-only MX records listed (i.e. a domain name with AAAA but no A
> record(s)). The common factor seems to be mimedefang.

Plain sendmail has got a similar issue, especially if the best MX is
IPv6-only.  I learnt that the hard way---and it speaks for the quality
of IPv6 testing that the "IPv6 considerations for SMTP" RFC (forgot
its number) doesn't even come close to mentioning this issue,
preferring to talk about bizarre reachability concerns. 8-P

Florian Weimer                <fweimer at>
BFK edv-consulting GmbH
Kriegsstraße 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99

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