[prog] Java mailserver component recommendations?

[Rachel McConnell]

I'm looking for a mailserver component for a personal project.  I've 
known of Apache James for a while; I'll do some looking for other 
options as well.  Anyone have any recommendations, positive or negative?

My requirements are:

* written in Java (or, I suppose, has a Java interface to it)
* recent development activity
* more than minimal documentation OR nice developers who will answer 
questions ;)
* open-source
* free or low cost - I don't mind paying a Reasonable Amount, although I 
haven't fully defined Reasonable yet

Thanks!
Rachel