Hello, could
reject_unknown_reverse_client_hostname in the smtpd_recipient_restrictions be responsible, since there are dns resolution issues for the hostname. Florian Am 14.02.2025 um 10:30 schrieb Nikolaos Milas via Postfix-users:
Hello, The two mail gateway servers (MX 10 mailgw1.noa.gr and ΜΧ 20 mailgw3.noa.gr) of our org (noa.gr), running Rocky 8 and Postfix 3.9.1, are working fine (for a long time - thanks Wietse), but we are having issues with fortimailcloud servers. These servers seem to be trying to connect but disconnect without any other action. Users (recipients in our domain) are reporting that they are not getting mail from users at dias.com.gr domain. Senders on domain dias.com.gr are reporting that their mails are not getting delivered to users on our domain (noa.gr), but we have not logged any failed delivery attempts (except from the connect/disconnects I mentioned). We have noticed that mail connections come from 154.52.2.0/24 and advertise DNS name: smtpfra7.fortimailcloud.com Successful deliveries are occurring rarely; we mostly log connect/disconnects. As an example: Logs of failed connections on mailgw1.noa.gr (MX 10) (indicative, there are high numbers of those): ... Jan 14 10:37:12 mailgw1 postfix/smtpd[1125361]: warning: hostname smtpfra7.fortimailcloud.com does not resolve to address 154.52.2.249: Name or service not known Jan 14 10:37:12 mailgw1 postfix/smtpd[1125361]: connect from unknown[154.52.2.249] Jan 14 10:37:12 mailgw1 postfix/smtpd[1125361]: lost connection after CONNECT from unknown[154.52.2.249] Jan 14 10:37:12 mailgw1 postfix/smtpd[1125361]: disconnect from unknown[154.52.2.249] commands=0/0 ... Jan 14 10:49:00 mailgw1 postfix/smtpd[1125361]: warning: hostname smtpfra7.fortimailcloud.com does not resolve to address 154.52.2.157: Name or service not known Jan 14 10:49:00 mailgw1 postfix/smtpd[1125361]: connect from unknown[154.52.2.157] Jan 14 10:49:00 mailgw1 postfix/smtpd[1125361]: lost connection after CONNECT from unknown[154.52.2.157] Jan 14 10:49:00 mailgw1 postfix/smtpd[1125361]: disconnect from unknown[154.52.2.157] commands=0/0 ...
...
Follows "postconf -n" and master.cf (from mailgw1; mailgw3 is identical): ============================================================================================================= [root@mailgw1 postfix]# postconf -n
...
smtpd_recipient_restrictions = check_client_access hash:/etc/postfix/blacklisted_clients check_client_access hash:/etc/postfix/amavis_bypass_clients check_sender_access hash:/etc/postfix/amavis_bypass_senders check_sender_access hash:/etc/postfix/blacklisted_senders check_sender_access pcre:/etc/postfix/blacklisted_maillists reject_unverified_recipient reject_unauth_destination check_recipient_access hash:/etc/postfix/protected_destinations permit_mynetworks reject_invalid_hostname reject_unauth_pipelining reject_non_fqdn_sender reject_unknown_sender_domain reject_non_fqdn_recipient reject_unknown_recipient_domain reject_unknown_reverse_client_hostname reject_rhsbl_client dbl.spamhaus.org reject_rhsbl_sender dbl.spamhaus.org reject_rhsbl_helo dbl.spamhaus.org permit
... _______________________________________________ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
