hi,
You want to develop mail feature in your website right.mailing system is different from intranet and internet .You've to connect one smtp server for sending mails from your website.
And for receiving mails you've to use pop3 or someother protocols which are rapidly used in present marketing.
If you want to use some third party services like...
There are so many services available in internet.
otherwise,you've to develop entire code for mailing system in your website
i think it take somemore time to do that feature.
I'm giving some link for pop3 client in asp.net
http://www.codeproject.com/KB/IP/despop3client.aspx
the above link is used for reading inbox mails from mail server.
And now how to send mail
http://forums.asp.net/t/971802.aspx
The above link used for sending mail.
I hope u'll understand what I said.
all the best.