you not clear that which tech. you want to use.there is more option for
that perpuse in java.
you can use servlets programming for mail  and chating server.
you want in more detial then please wait few days.

U can use the steps as below:

- import classes from javax.mail and javax.mail.internet packages
- create a Properties object and put value of smtp host in its property
"mail.smtp.host". Please note that this host should be able to/configured to
send mails outside
- create a Session object with this property, like Session session =
Session.getDefaultInstance([prop obj],null)
- create a message object using session object, like Message msg = new
MimeMessage(session)
- set from, to, subject, text using appropriate set methods on msg object.
- Use the static send method of Transport class to send mail.