On Tue, Sep 21, 2021 at 08:31:15PM +0200, Marc Haber wrote: > Please check whether your system is correctly configured to find the > host name. Information can be found on > https://wiki.debian.org/PkgExim4UserFAQ#How_does_exim_find_out_its_host_name_to_use_in_HELO.2FEHLO.3F > > Please report back about your results.
It's not quite clear to me what you want me to report, but I will try. We never had a problem of HELO localhost.localdomain, only of HELO <shortname>. After commenting out the MAIN_HARDCODE_PRIMARY_HOSTNAME line (and running update-exim4.conf and service exim4 restart, I got # exim4 -bP|grep ^primary_hostname primary_hostname = <shortname> I then did "apt purge libnss-myhostname" (and again update and restart) and now the same command produces: primary_hostname = <longname> When trying "telnet <hostname> smtp", the mail server identifies itself with the longname and replies to "helo bla" with 250 <longname> Hello <longname of telnet machine> [<ip>] So apparently libnss-myhostname bug is at fault. Looking at bug report #756224, it has not been fixed in 7 years, so it is unlikely to be fixed soon, and a conflict between exim4 and libnss-myhostname seems appropriate. I don't remember explicitly installing libnss-myhostname, so it most likely came with some other package; however, removing it did not lead to other package removals, so I don't know how it came in. - anton