I have Nginx setup for dynamic hosts (similar to Apache mass vhosts) and this is causing an issue with Postfix.

This is causing an issue for the server sending emails - Message-ID with no domain name.

In my server block I have server_name ~(?<domain>.+)$;

When Postfix sends an email, the message ID doesn’t show a FQDN, it shows @~(?<domain>.+)$, the same regex used for my server_name.

Does anyone know how to get Nginx/Postfix to play nicely together? The only thing I can think of is that Nginx isn’t passing the server_name properly.