Email via sendmail not working

Hi,

I'm trying to get build notifications from CI to work, but I'm all out of luck! I've tried both using sendmail and setting up the SMTP config, but none of those affect CI, it seems.

I don't get any errors in production.log or in sidekiq, but the mail log reveals an issue, which I can't seem to figure out.

Here's the log when gitlab is sending:

May  2 10:48:19 ubuntu postfix/pickup[11898]: B839D18AC34: uid=1003 from=<gitlab-runner>
May  2 10:48:19 ubuntu postfix/cleanup[15601]: B839D18AC34: message-id=<20160502084819.B839D18AC34@msarepo>
May  2 10:48:19 ubuntu postfix/qmgr[11899]: B839D18AC34: from=<gitlab-runner@FQDN>, size=551, nrcpt=1 (queue active)
May  2 10:48:19 ubuntu postfix/local[15603]: B839D18AC34: to=<root@FQDN>, orig_to=<root>, relay=local, delay=0.05, delays=0.04/0/0/0, dsn=2.0.0, status=sent (delivered to mailbox)
May  2 10:48:19 ubuntu postfix/qmgr[11899]: B839D18AC34: removed

I don't understand why it's trying to send to gitlab-runner? And the relay is all wrong, too. And, I get the same entries in the log, wether I'm using sendmail or the manually configured SMTP, so something is not right...

When I try sending an email manually, using echo "My test email being sent from sendmail" | sendmail user@FQDN, I get this in the mail log:

May  2 10:52:50 ubuntu postfix/pickup[11898]: 0A3DF18AC31: uid=1000 from=<sender>
May  2 10:52:50 ubuntu postfix/cleanup[16215]: 0A3DF18AC31: message-id=<20160502085250.0A3DF18AC31@FQDN>
May  2 10:52:50 ubuntu postfix/qmgr[11899]: 0A3DF18AC31: from=<sender@FQDN>, size=281, nrcpt=1 (queue active)
May  2 10:52:50 ubuntu postfix/smtp[16217]: 0A3DF18AC31: to=<user@FQDN>, relay=SMTP_FQDN[smtp_ip]:25, delay=0.24, delays=0.02/0/0.05/0.17, dsn=2.6.0, status=sent (250 2.6.0 <20160502085250.0A3DF18AC31@FQDN> [InternalId=24046619] Queued mail for delivery)

Any pointers on what's going wrong?

Using latest version of the onmibus-package on Ubuntu 14

Edit:

When creating a new user, email is sent properly, and logs show the same as when I manually use sendmail