Do you have questions on writing one? or are you just looking for a script?

Where I'm at now, it fits the bill for the site it's being used on and not much else... try'n plug any other form element into it and see how fast you have to write more code.
Unless you know your way around regular expressions and want to spend a few hours adding functions, I'd steer clear of my script

A more mature/flexible formmail script I was using prior to doing my own was the one here:
http://www.boaddrink.com
It seems good and was quite easy to set up, and as well as having the features there's a support forum for it... so any setup questions/problems you have with it are probably already answered.

tbh I could have saved myself hours of wheel-reinventing if I'd just had the patience to figure out how to customise it the way I wanted... oh well.