Hi all, I've seen some really strange things happening these days.
Recently I asked my ISP to set the PTR records for my ipv4 address from the default (something like host-1-2-3-4.provider.net) to my own domains (mydomain.de and myotherdomain.net). Fine. Then I changed myhostname = host-1-2-3-4.provider.net to myhostname = mydomain.de and Postfix used that for it's helo greeting. Fine. Two days ago, I suddenly received emails from local services originating from r...@host-1-2-3-4.provider.net rather than from r...@mydomain.de or root@host as usual, which confused me. I looked into Postfix configuration and saw this: Before (what I configured): smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU) myhostname = mydomain.de Suddenly (whoever did that): smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU) myhostname = host-1-2-3-4-provider.net Then I realized that my provider accidentially changed the PTR back to the default, which was fixed a couple of hours later. I changed main.cf back to myhostname = mydomain. Emails from local services continued to come from r...@host-1-2-3-4.provider.net for another couple of hours, until everything went back to normal. Just a few minutes ago I got an email from r...@host-1-2-3-4.provider.net again, and looked at Postfix's main.cf. Yes, again myhostname was changed to host-1-2-3-4-provider.net, this time the PTRs were okay (but may have been reverted to default and back just before I checked). I am running my own DNS (bind9) on the same machine as Postfix. All local DNS queries are processed by this server. This server is also authoritative for the forward zones of both domains, and the ipv6 reverse zones, but not for ipv4 reverse zones, of course. What the hell happens here? Why is main.cf changed, and who's doing that? Would it change back if I just wait? How do local services using the mail command know about the PTRs? Confused, Robert -- Robert Senger
