CMSs not sending emails (but php mail works)

Question

I have a Ubuntu 14.04 VPS with a few sites.

If I run php -r "mail('[email protected], 'test', 'test');" this gets delivered, but I have a couple of CMSs (Drupal and dokuwiki) that don't send any emails, including basic password reminder/registration.

I have checked and I am not blacklisted. Where should I look to start debugging ?

Edit: it seems the problem is that I have the incoming emails using a third party while postfix try to deliver the email locally (maybe looking at the alias file?).

How can I force postfix to NOT try to deliver the email locally ?

Answer 1

The solution was to remove $mydomain (or myownservername.xxx if set explicitly) from mydestination variable in /etc/postfix/main.cf.

Found it in this post on ServerFault.