Telnet to port 25 of the machine you want the
mail to appear to originate from. Enter your message as in this example:

HELO bellcore.com
MAIL FROM:Voyager@bellcore.com
RCPT TO:president@whitehouse.gov
DATA

Please discontinue your silly Clipper initiative.
.
QUIT

On systems that have RFC 931 implemented, spoofing your "MAIL FROM:" line
will not work. Test by sending yourself fakemail first.
For more information read RFC 822 "Standard for the format of ARPA Internet
text messages."

13. How do I fake posts to UseNet?

Use inews to post. Give inews the following lines:

From:
Newsgroups:
Subject:
Message-ID:
Date:
Organization:

For a moderated newsgroup, inews will also require this line:

Approved:

Then add your post and terminate with .
Example:

From: Eric S. Real
Newsgroups: alt.hackers
Subject: Pathetic bunch of wannabe losers
Message-ID:
Date: Fri, 13 Aug 1994 12:15:03
Organization: Moral Majority

A pathetic bunch of wannabe losers is what most of you are, with no
right to steal the honorable title of `hacker' to puff up your silly
adolescent egos. Get stuffed, get lost, and go to jail.

Eric S. Real

^D

Note that many systems will append an Originator: line to your message
header, effectively revealing the account from which the message was
posted.