On Sun, 16 Feb 2020, li...@lazygranch.com wrote:
Some gmail gets through, some doesn't. Is there a time limit on the DNS
check? A google search finds several timers, but nothing specific to
DNS.
Log:
Feb 17 06:18:10 mydomain postfix/smtpd[2619]: connect from
unknown[209.85.219.177]
Feb 17 06:18:10 mydomain postfix/smtpd[2619]: Anonymous TLS connection
established from unknown[209.85.219.177]: TLSv1.2 with cipher
ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)
Feb 17 06:18:10 mydomain postfix/smtpd[2619]: NOQUEUE: reject: RCPT from unknown[209.85.219.177]:
550 5.7.1 Client host rejected: cannot find your reverse hostname, [209.85.219.177];
from=<some.per...@gmail.com> to=<m...@mydomain.com> proto=ESMTP
helo=<mail-yb1-f177.google.com>
Feb 17 06:18:10 mydomain postfix/smtpd[2619]: disconnect from
unknown[209.85.219.177] ehlo=2 starttls=1 mail=1 rcpt=0/1 bdat=0/1 quit=1
commands=5/7
Clearly the server is legit.
https://bgp.he.net/ip/209.85.219.177
AS15169 IRR Valid 209.85.128.0/17 Google LLC
Are you using your own local DNS server (unbound or such) or a public one?
If your DNS resolving is so unreliable, I would suggest not rejecting
e-mails merely because you can't find/verify the rDNS.
Cheers.
