Send IM into SL from Website

I am guessing using PHP, I am developing a web site where people use their SL name when they register - it is for a small nonprofit group. Once they register, I would like to have a message sent to SL so the person knows an account was created using their SL name and thus verify its authenticity. Any idea where to start? Can I do it as an email?

The best way to do it is to require registration to origionate from SL. That way you already know it was requested by them.