[TYPO3] get hooked up with other extension

[rocky Ou]

Hey,

I'm learning to develop a clients information management plugin. In the 
extension, I need to have a mail function. I think tmail really meet my 
needs. In tmail EXT, I need to input which person will receive the 
email. I want my ext user select receipient emails and they will be used 
by tmail and I want to use tmail's FE interface. Is this possible to 
achieve? Can any of you give me some hint please?

Thanks a lot in advance!
Rocky