My mails from root@my.domain.com are just being queued and when clicking deliver now I get;

Message XXXXXXXXXXXXX is not frozen
error setting gid
LOG: MAIN PANIC
User 0 set for local_delivery transport is on the never_users list
LOG: MAIN
== root@my.domain.com R=localuser T=local_delivery defer (-29): User 0 set for local_delivery transport is on the never_users list

I found this on exim FAQ

Q0511: Whenever my system filter uses a mail command to send a message, I get the error User 0 set for address_reply transport is on the never_users list. What does this mean?

A0511: The system filter runs as root in Exim 4, unless you set system_filter_user to specify otherwise. When you set up a delivery direct from a system filter (an autoreply is a special kind of ``delivery'') the transport runs as the same user, unless it has a user setting of its own. Normally, deliveries are not allowed to run as root as a security precaution; this is implemented by the never_users option.

The easiest solution is to add this to your configuration:

system_filter_user = exim
The system filter then runs as exim instead of root. Alternatively, you can arrange for autoreplies from the system filter to use a special transport of their own, and set the user option on that transport.


However when I set this I get user exim doesn't exist.