I tried whitelisting the offensive host as a forward host (my understanding was that mailcow will not reject mail from such hosts and forward it).
But this is what happens:
18.03.2022,
19:35:16 info disconnect from unknown[192.168.99.71] ehlo=1 mail=1 rcpt=0/1 commands=⅔
18.03.2022, 19:35:16 info lost connection after RCPT from unknown[192.168.99.71]
18.03.2022, 19:35:16 info NOQUEUE: reject: RCPT from unknown[192.168.99.71]: 554 5.7.1 otheruser@otherorg.com: Relay access denied; from=user@myorg.com to=otheruser@otherorg.com proto=ESMTP helo=<[127.0.0.1]>
18.03.2022, 19:35:15 info connect from unknown[192.168.99.71]
18.03.2022, 19:35:15 info WHITELISTED [192.168.99.71]:35980
18.03.2022, 19:35:15 info Look up 192.168.99.71 on whitelist, result 200 PERMIT
18.03.2022, 19:35:15 info CONNECT from [192.168.99.71]:35980 to [172.22.1.253]:25``
Mailcow acknowledges that the server is whitelisted and still it rejects the message. I don’t know what is going on.
And I am running out of ideas how to get mailcow to accept mail from this server.😭