Sep 19 06:48:49 mx0 postfix/smtpd[17545]: NOQUEUE: reject: RCPT from server1.example.com[10.1.2.137]: 554 5.7.1 <logcheck@server1.example.com>: Sender address rejected: forged mail; from=<logcheck@server1.example.com> to=<etbe@example.com> proto=ESMTP helo=<server1.example.com>
I have two servers with consecutive IP addresses named server0 and server1. They both try to send mail to my mail server, when I have a cron job or swaks send mail server1's mail is rejected with messages like the above and server0 mail goes through. The forward and reverse DNS entries all look to be good and the SPF entry is also correct.
Is it doing sender address validation in any way, eg is the address represented by "logcheck@server1.example.com" a valid address, and/or is server1 making that verification correctly? James