Thanks for the reply. The warning says that "hostname does not resolve to address" (case #4) but then the log says that connection is rejected because it cannot find a hostname (case #2). So which one is the actual rejection reason? Doesn't it feel a bit confusing?
Regards <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Без вирусов. www.avast.ru <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> пн, 23 нояб. 2020 г. в 17:40, Wietse Venema <wie...@porcupine.org>: > Eugene Podshivalov: > > Hi all, > > I have the following config > > > > > smtpd_client_restrictions = > > > reject_unknown_client_hostname > > > smtpd_helo_required = yes > > > smtpd_helo_restrictions = > > > reject_invalid_helo_hostname, > > > reject_non_fqdn_helo_hostname, > > > reject_unknown_helo_hostname > > > smtpd_sender_restrictions = > > > reject_non_fqdn_sender, > > > reject_unknown_sender_domain > > > > > > but still get warnings like this > > > > > postfix/smtpd[24986]: warning: hostname > server17-ams1.internet-census.org > > > does not resolve to address 107.6.163.34: Name or service not known > > > postfix/smtpd[24986]: connect from unknown[107.6.163.34] > > > postfix/smtpd[24986]: NOQUEUE: reject: CONNECT from > unknown[107.6.163.34]: > > > 450 4.7.25 Client host rejected: cannot find your hostname, > [107.6.163.34]; > > > proto=SMTP > > > postfix/smtpd[24986]: disconnect from unknown[107.6.163.34] ehlo=0/1 > > > quit=1 commands=1/2 > > Postfix logs this warning, so that you can understand WHY a client > may be rejected with reject_unknown_client_hostname, and how the > problem may be fixed. > > 1 - A problem with the address->name mapping (lookup failed) > > 2 - A problem with the address->name mapping (the mapping does not > exist). > > 3 - A problem with the name->address mapping (lookup failed) > > 4 - A problem with the name->address mapping (the mapping does not > exist) > > 5 - A problem with the name->address mapping (the mapping does not > match the client IP address) > > In your case the probkem was #4. > > Wietse >
