FreeBSD.org MX servers refusing mail from host via ipv6

[Paul van der Zwan]

Hi,
It looks like the freebsd.org <http://freebsd.org/> servers are refusing mails from unresolvable hosts:

2021-10-01T11:49:53.891959+02:00 mail.info <http://mail.info/> MyMailRelay sm-mta[78439] 1918bDet078021: to=<freebsd-questions at freebsd.org <mailto:freebsd-questions at freebsd.org>>, ctladdr=<XXXXXX at vanderzwan.org <mailto:XXXXXX at vanderzwan.org>> (544/544), delay=01:12:35, xdelay=00:00:03, mailer=esmtp, pri=336150, relay=mx66.freebsd.org <http://mx66.freebsd.org/>. [IPv6:2610:1c1:1:606c:0:0:19:5], dsn=4.7.25, reply=450-4.7.25 Client host rejected: cannot find your hostname, [2001:1af8:4700:a116:1::42], stat=Deferred: 450-4.7.25 Client host rejected: cannot find your hostname, [2001:1af8:4700:a116:1::42]

For IPv6 this seems like a very strict requirement as it’s almost impossible to get reverse DNS working for autoconfigured IPv6 adresses ?

Is there an IPv4 only alias I can route mail to for freebsd.org <http://freebsd.org/> domain ?

TIA
	Paul