Am Sun, 03 Mar 2024 17:23:22 +0000 schrieb Gareth Evans via mailop <[email protected]>:
> I am curious about the exact mechanism of PTR checks, and couldn't > find it in RFC5321 so presume it's not actually part of SMTP. Most server require that the PTR points to a domain name like mail.example.org and that has the corresponding A/AAAA records that point to the IP address. E.g. 3.2.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa. IN PTR mail.example.org mail.example.org IN AAAA 2001:db8::123 IIRC the SMTP standard doesn't require that, but many dialup/home users don't have that and they were often used to send spam, so MTAs like sendmail offer a feature to check the PTR and reject connections that don't have a matching PTR. Most bigger mail server want a proper PTR. Let your ISP delegate the reverse zone for your IP ranges to your DNS server or let them set the PTRs you want. _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
