Date: Fri, 1 Oct 2021 23:23:25 +0200 From: Paul van der Zwan <paulz42@gmail.com> To: Doug McIntyre <merlyn@geeks.org> Cc: freebsd-questions@freebsd.org Subject: Re: FreeBSD.org MX servers refusing mail from host via ipv6 Message-ID: <7F187395-7DAC-440E-9F3A-259DAB7A63C9@gmail.com> In-Reply-To: <YVdyi10zTG3MiQWd@geeks.org> References: <8BF8713A-6677-4BAD-A61B-9A7B5D9CC297@gmail.com> <YVdyi10zTG3MiQWd@geeks.org>
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> On 1 Oct 2021, at 22:41, Doug McIntyre <merlyn@geeks.org> wrote: > > On Fri, Oct 01, 2021 at 02:37:08PM +0200, Paul van der Zwan wrote: >> It looks like the freebsd.org servers are refusing mails from unresolvable hosts: > > > As much as I think it is worthless security, this has been the > standard for quite some time on IPv4, and IPv6 copied it along. I'm > not sure you'd find more than a handful of mail servers out there that > would let a mailserver without a reverse PTR setup to talk to them > either on IPv4 nor IPv6. So, if you don't get to control your IPv6 > reverse PTR, you probably shouldn't be sending email from that > machine, because none of it is going to get through. > My own mailserver refuses to relay when no PTR is found but accepts mail destined for the local domain. Which I considered an acceptable compromise. > GMail certainly will never let you talk on IPv6 without a reverse PTR record. Gmail has no problem whatsoever accepting mail from my mailserver. > I'm sure FreeBSD MX is just following "best" practices. > This is the first time I ever ran into this so FreeBSD MX seems to be an exception. >> For IPv6 this seems like a very strict requirement as it’s almost impossible to get reverse DNS working for autoconfigured IPv6 adresses ? > > Mail servers typically have static IP addresses? Servers that aren't > mail servers but still send email should probably relay through a > fixed submission server. > >> Is there an IPv4 only alias I can route mail to for freebsd.org domain ? > > You could always configure your email server to only be sending IPv4 > email to certain domains. Ie for postfix, something like > https://tanguy.ortolo.eu/blog/article109/google-ipv6-smtp-restrictions > Having an ipv4 only MX would be nice but I guess I’ll have to figure out a local solution. Running sendmail here so the postfix solution will not work but I think I can add an IPV4 only mailer and use mailertable to route domains like freebsd.org <http://freebsd.org/>; to that mailer. Thanks Paul > _______________________________________________ > freebsd-questions@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" >help
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