Recently, I installed iredmail on my VPS and configured DNS records (including ptr). It confirms nslookup:
nslookup zelenin.top Name: zelenin.top Address: 188.8.131.52 nslookup -query=mx zelenin.top zelenin.top mail exchanger = 5 mail.zelenin.top. nslookup 184.108.40.206 220.127.116.11.in-addr.arpa name = mail.zelenin.top.
I also configure DKIM, SPF, DMARC and google-site-verification records. Then I connected to the VPS by mail client and tried to send mail to gmail. But it was not delivered, and I got an answer:
host gmail-smtp-in.l.google.com[2a00:1450:4013:c01::1a] said: 550-5.7.1 [2a00:7c80:0:58::1:600] The IP address sending this message does not 550-5.7.1 have a PTR record setup. As a policy, Gmail does not accept messages 550-5.7.1 from IPs with missing PTR records. Please visit 550-5.7.1 https://support.google.com/mail/answer/81126#authentication for more 550 5.7.1 information. m65si25883044wmd.98 - gsmtp (in reply to end of DATA command)
I don not know what information may be helpful or what can cause this. Thank you.