To run web-based mail clients you'll need to be running a web-server. GUI apps exist, depending on the desktop you're using (kmail for KDE, for instance).
2. Is there any GUI & web based application which can be used for the mail application written above ? i have heard of webmail, squirrel mail & their plugins....something of that sort, etc. but how to use that on the localhost for all my 10 users ?
man mail will tell you all you need to know about this mail client. Other command line email clients include mutt and elm.
3. if i run # mail ,
Mail version 8.1 6/6/93.
"/var/spool/mail/root": 8 messages 8 unread
Is this the default mail application which is running ?? what services it uses ? sendmail or postfix ? pliz write all the services it uses ? How can i use the command line to send mails ?