Unless you have a ton of time and are paid only $10 /hour its probably cheaper and easier to build on top of:
http://www.aspnetpop3.com/
than make your task 100 x easier. These are really robust components by one of the best programmers in the country and a steal at his prices compared to developing it yourself.

I have had so far just one component:
http://www.quiksoft.com/ Easy Mail.Net
to develop web  mail but I amm reviewing the one u sent me. Charles during the development  the stage I am worried about is the sending email with attachments, I mean how the attachments will be check for the size, first uploaded to server and then to be sent by email, how can I save sent emails on server side, should I use a sql datable in this regard and for the read messages I am thining that I should surely have a table storing the email IDs of read messges to differentiate among the messages which are read and un-read while displaying them on the web page, any way I will bugg u again once I have started development.

check the following link . asp.net-informations.com/.../asp-email.htm . It is a simple program to send email from asp.net application.

Thomas.