how to develop inbox system tool

hello,

i'm developing a new web 2.0 website

i have a problem in the contact us scenario

the user will contact the website admin with a problem or a complain

and the admin will contact him back with answer for his problem,

and the user may contact him again ..

i want the aspx form to show them like the inbox in facebook  ( the inbox including many messages, every message have many threads )

so how can i make that with database, and with the aspx form, and which control should i use to show it like this .

thanks
...