exim running as user 104

I'm running Debian and I want exim to only be used for outgoing mail (notices, warnings, etc…)

I modified my config file at /etc/exim/exim.conf.O and uncommented this line then I restarted the service.

local_interfaces = 127.0.0.1

This doesn't appear to work, I can still send mail to the box.

Some time ago I upgraded to exim4 and in my /etc directory I have both the monolithic config and the directory config (under exim4)

1. This might sound stupid but how do I know which one exim is using?

2. When I restarted the process exim4 is now running as user 104, and not root as it used to. Is this normal?

Thanks for any tips!