Gmail does not accept mail from a new VPS server with PTR setup

I have PTR records setup but I am not able to deliver mail to Gmail accounts:

host gmail-smtp-in.l.google.com[2607:f8b0:4004:c08::1b] said: 
550-5.7.25 [2a01:4ff:f0:a7b6::1] The IP address sending this message does not
550-5.7.25 have a PTR record setup, or the corresponding forward DNS entry does 
550-5.7.25 not point to the sending IP. As a policy, Gmail does not accept 
550-5.7.25 messages from IPs with missing PTR records. Please visit
550-5.7.25  https://support.google.com/mail/answer/81126#authentication for more 
550-5.7.25 information.
u1-20020ac87501000000b00315c38791casi6985465qtq.683 - gsmtp (in reply to end of DATA command)

Can someone please walk me through on how to setup my PTR records correctly. I am hosted on Hetzner Cloud and used Rainloop to create the email accounts.

Solution

Your PTR record for IPv6 is setup correctly (and strictly speaking it seems to be no longer required by Gmail).

Saying that one hint is in the message Gmail sends to you:

or the corresponding forward DNS entry does 550-5.7.25 not point to the sending IP

Which is the case here:

tkepczyn-linux1:~> dig mail.saveneur.com aaaa +short
tkepczyn-linux1:~>

There is no mapping from the mail.saveneur.com back to the IPv6 address.

Saying the above please also consider setting up SPF record. If it is missing this may be the real cause of this error. Unfortunately I cannot help with this as you haven't provided the sending domain name.

Comments (2)

+0 – I edited post to show newly added AAAA record. Would that suffice? — Jul 27, 2022 at 18:28
+2 – AAAA record requies full IPv6 address, not a network address. Just put 2a01:4ff:f0:a7b6::1 there. I don't know if it would suffice, ask Google. But according to the message it should. — Jul 27, 2022 at 18:39

External Links

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References

https://serverfault.com/questions/1106769