This a reference for future-me, and possibly someone pulling off an all-nighter
trying to get
nullmailer to use the correct “remote”.
What is nullmailer and why use it?
Nullmailer is a simple mail transfer agent that can forward mail to a remote mail server (or a bunch of them).
I use Emacs to send email, and it can be configured to talk to a remote SMTP
server to send email. But, this blocks Emacs until the email is sent and the
connection closed. This is annoying, and having
nullmailer installed locally
basically lets Emacs delegate this job without blocking.
Why multiple remotes?
I have multiple email accounts, and I’d like to use the correct remote server for sending email based on the FROM address.
nullmailer to have some configuration to be able to specify this.
But, it turns out that
nullmailer just forwards the email to all the
configured remotes until one of them succeeds.
How do we, then, send email from the correct remote SMTP server?
Currently, I have two remotes - my personal domain (
@muse-amuse.in) and GMail.
Having GMail as the first remote in
nullmailer’s configuration wouldn’t let me
send emails from my personal domain. GMail seems to agree to send the email
@muse-amuse.in, but overwrite the MAIL FROM address and change it
to my GMail address.
@muse-amuse.in has to be the first remote. But, this server also seemed to
accept and send emails with a
FROM address. This was causing
emails sent from my GMail ID to go into spam, as expected.
I had to reconfigure this mail server to reject relaying mails that didn’t
belong to the correct domain names – i.e., reject relaying emails which had
@gmail.com in the
smtpd_sender_restrictions had to modified to have
along with other values, and the
smtpd_sender_login_maps had to be set to
allow only the
@muse-amuse.in domain. This serverfault answer explains this in