SMTP is the protocol which is used to send mail over the internet.
When we login to our account and send a mail the smtp protocol will send it to the smtp server which will send it to the pop3 server and then it gets to the receiver email account.
The main bug in this system is that the SMTP server access dosen’t need any authentication, means when u want to send data to any of the email account you need not to provide the your identification or the email id and password you can just login with any email id and send email.
But the receiver has to give his e mail id and password as the pop3 server needs a authentication.
thus, using this bug even a leyman can send a fake mail with any user id and fool the receiver.
This kind of java script are already available on net so u can get it from any where.
Now the main crux here is that the mail can be trace and the ip can be known to the tracer, now a days terrorist are using such bugs to send email and may be traced. So please dont use this method for any destructive or negative purpose.
As per the indian laws it may be punishable to send fake mail via internet bus there is no such juridiction in law for sending fake mail through GPRS and this the loop hole.
So once you got the site from web for fake mail use it to send fake mail via GPRS and enjoy.