confirmation mail sent up from host without reverse DNS

Hello,

I tried to resubscribe gcrypt-devel today via the admin interface,
which failed with:
Request data update...Invalid list address gcrypt-devel(at)gnupg.org: RCPT response: 550 Reverse DNS lookup failed for host 2a01:4f8:e0:11e6::2.

and indeed the listed IP has no reverse DNS which does not look like a
vaild configuratiion for a mail server.

cu Andreas

-- 
`What a good friend you are to him, Dr. Maturin. His other friends are
so grateful to you.'
`I sew his ears on from time to time, sure'