Which hostname is exim sending ?
One can find the HELO name in exim4's logs. Stop the exim4 daemon, then restart it manually with debugging enabled :
/usr/sbin/exim4 -bd -d+all 2>&1 | egrep 'HELO|EHLO'
2>&1|egrep 'HELO|EHLO' part is optional, it just redirects stderr to stdout, then pipe the log to
egrep, which will filter everything but lines containing HELO or EHLO).
Send an email and there should be one or two lines in the following form :
SMTP>> EHLO foobar.example.com
The HELO name is
There are also several useful online checking tools which provide this information (and many useful others), e.g. :
- https://www.mail-tester.com (beware, only 3 free email checks per day) ;
- email@example.com (free) ;
- firstname.lastname@example.org (most of its feedback is not free, but for this purpose it is).
How do I change it ?
Instead of editing the transport file as suggested by David, I'd rather use exim4 constant definitions (?) and set the name in
/etc/exim4/conf.d/main/00_local_settings (in split configuration), e.g. :
Don't forget to run
update-exim4.conf before to restart exim4.
I set primary_hostname […] in /etc/exim4/exim4.conf.template
As mentioned by David, this is probably not the best idea. In split configuration, you can set the primary hostname by adding
MAIN_HARDCODE_PRIMARY_HOSTNAME = subdomain.example.com
/etc/exim4/conf.d/main/00_local_settings. It seems it would be
PRIMARY_HOST_NAME in monolithic exim4 configuration.