Web Email server and client?

i want to implemnet the functionality of web email server and client. please suggest the best email server and client, free will be preferred off course.

Web Email server and client?
For Windows, Zimbra and MailEnable are open source mail servers.


http://www.zimbra.com/index.html


http://www.mailenable.com/





For Linux, Qmail and SendMail are open source mail servers.


http://www.qmail.org/top.html


http://www.sendmail.org/
Reply:I don't understand, whether you want to do the coding for email server and cilent or you want to download a free one from Internet. for coding asp.net/asp can be used. and ideas can be taken from the popular email sites on the net.