On Fri, May 08, 2020 at 06:38:32PM +0200, michae...@rocketmail.com wrote: > Hi all, > > > I've a generic question to all more experienced than me postfix users here: > Is it nowadays (reasonable) possible to run postfix with IPv6 only? E.g > "mail.example.com" and "smtp.example.com" with only ipv6 AAAA records in the > DNS, no A / ipv4 anymore? > > > Michael > > > ----- EOM for impatient readers :-) ------- > > > Hi patient readers :-) > > reason for my question: > > I'm running my own small postfix/dovecot etc. environment on a VPS. Running > fine for years now, after some initial work to get my sent emails not > delivered as junk. > spf record exists for my few domains, dkim is active and passes everytime, > dmarc entry is active. > https://www.mail-tester.com gives me 10/10 :-) > > All relevant for me email providers are accepting my emails without any > issue, for long, except Microsoft hotmail/outlook. Registered for SNDS, and > JMRP feed is activated. > IPv4 adress is "clean" and fine for outlook.com. > > BUT nevertheless all emails from me to any outlook.* or hotmail.* recipients > is delivered to their junk folder. > > I strongly believe that this is because of the (hopefully) only "issue" left > I know about: My PTR. > > As I have a small VPS with only one IPV4 included in price, I've set the PTR > to "example.com" and not to "mail.example.com", which is the fqdn for my > outgoing postfix sent mail. > Of course I know that this is a "should not", but as there's a lot of stuff > running e.g. on Apache on this machine, a nextcloud instance, a TYPO3 > instance, roundcubemail, jitsi meet, ..., all on separate subdomains like > "cloud.example.com", "webmail.example.com", "meet.example.com" etc., I simply > don't like to have an "unclean" PTR, pointing not the main/base domain. > "Only" because of antispam. > > As said I have only one IPv4 for my VPS, but a /64 IPv6 subnet. > So more than enough IPv6 addreses to give each of my few domains amd not that > many subdomains a unique IPv6, with a corresponding PTR. > > I'm only not sure if there might be "IPv4-only" email providers out there, > whose emails might not be routed to my "IPv6-only" postfix.
I have a suggestion that works well for my similar email setup (small VPS providing a number of disparate services). Give your VPS a hostname that's unrelated to any of the services. Mine, for example, is "fenrir". Create an A / AAAA record for that hostname underneath your domain. Make the PTR record point to that hostname FQDN. Then you can point your MX records to that FQDN, and set up postfix to identify itself as that same name. Here's my DNS records: fenrir.routify.me - A - <my IP address> <my IP address> - PTR - fenrir.routify.me seangreenslade.com - MX - fenrir.routify.me And the greeting my Postfix gives: 220 fenrir.routify.me ESMTP Postfix With this setup, I haven't had any issues with mail deliverability. --Sean
