Email Forging

1)
Open a command prompt by clicking Start, Run, and type cmd in the box and press OK. You should get a black "Command Prompt" screen.
This can be done with the Terminal.app in Macintosh OS X and the command line in most Unix and Linux based operating systems.
2)
You will need an SMTP server address to proceed. Here is how to find one:
On the command-line, type nslookup.
Then, type set type=mx.
Finally, enter the name of any website, for instance, hazemdesigns.srhost.info.
This will return the following: Non-authoritative answer:hazemdesigns.srhost.info mail exchanger = 0 ASPMX.L.GOOGLE.COM..
The aspmx.l.google.com part is what you need. This is an SMTP server address.
Type exit to exit out of nslookup.
3)
Type telnet aspmx.l.google.com 25. 25 is the port number most SMTP servers use while sending email. Learn more about telnet.
4)
When the mail server responds, you can start typing SMTP commands.
5)
Start with helo blahblah.google.com. You may have to use your ISP's domain name for it to be accepted.
6)
If it says 'at your service' or something like that, continue with the address you want the mail to come FROM. So, to forge mail from Bill Gates, type mail from: billg@microsoft.com.
7)
If it says OK, type who you want the mail to go to, i.e. your friend's address. Type rcpt to: yourfriend@isp.com
8)
If it says Recipient OK, then you can type your message:
Type data and press Enter.
On the first line type Subject: yoursubject and press Enter twice.
Continue typing your message, such as 'I'm bill gates and want to send you a billion dollars'.
Put a single period (.) on a line by itself and press Enter to send your message. The server should say 'Message accepted for delivery'.
9)
You are done. You have just forged an email, and the recipient should be receiving it shortly.
10)
You can test to see if a given SMTP server is configured for forwarding by using online tools.
11)
TIPS:--->>>

hoaxMail, provides an online GUI for forging email. However, signup is required.
ZMail, an open-source application for linux, windows, and mac, does all of this for you. All you have to do is enter the from-address, the to-address, an smtp server, and your message.
This site provides a list of SMTP servers, provided by google, that work perfectly for forging emails. No authentication is required.
if you do not see the letters you type in your terminal application use the echo command.
Practice sending the message to yourself a few times until you get the hang of it.
Send it to yourself and view all the headers to make sure nothing that easily identifies you as the sender (like your computer name) shows up.
Servers which run enhanced SMTP will also accept 'ehlo blahblah.isp.com'. You may still need to use your ISP's domain name for it to be accepted.
It is normally easier just to find one of the many free websites that will allow you to send emails to anyone from anyone.
As mentioned in the warnings, most SMTP servers have relaying disabled. Many times you can overcome this by connecting to the ISP of the target email, since the server will accept it as a "local delivery" - i.e., if the target's address is "joe@company.com" telnet to "company.com" and forge it from there. Most "@company.com" mail servers are either "company.com", "mail.company.com" or "smtp.company.com".
If you use Windows telnet client and make a spelling mistake do not use the backspace key, instead, press ^] (CTRL+RIGHT BRACKET) to terminate the connection and try again. The backspace key is transmitted incorrectly and will result in odd characters appearing in the final message.
Some individuals believe running an open relay is a free speech issue, including John Gilmore, a long time Internet "personality" and one of the founders of the The Electronic Frontier Foundation. As a result most ISPs do not accept mail from Gilmore's servers.