mail server config

Hi,
Sorry if this is a stupid one. There seems to be very little in the way of 
mail configuration options. How does gnats send out it's notification emails?
Do I need mail software installed on the same machine as the gnats server, or 
can I get it to route through another smtp server located on the network?
If I have to install software locally, what specific software is required?

-- 
Chris Jensen
[email protected]

Public Key: http://drspirograph.com/public_key/

Wait: Did you know that there's a direct correlation between the decline of
Spirograph and the rise in gang activity?  Think about it.
- Dr Spirograph (The Simpsons)