I setup a clean iRedMail installation on a new server. I followed the instructions here: https://docs.iredmail.org/install.iredmail.on.debian.ubuntu.html and then setup the dns records like so: https://docs.iredmail.org/setup.dns.html I also added a certbot certificate: https://docs.iredmail.org/letsencrypt.html
I can now receive email from all other email providers and can send email to other users of my domain. But I cannot send email to other email providers, it doesn't even end up in the spam folder.
After some research i found out that my emails are missing a dkim signature which is the most likely reason they aren't picked up by other servers.
I did the amavisd-new testkeys test and passed, although I'm pretty sure it doesn't work, since it also works if I don't setup any DNS records.
So my questions are:
- shouldn't my emails be DKIM signed for some reason?
- which service is responsible for adding DKIM headers to emails?
- Where can I find out why it doesn't sign my mails?
Turns out Amazon blocks outgoing traffic on port 15 by default. Took me a while to figure out. There was no problem with DKIM.