It's a lot easier to do that by just telneting to port 25 on the SMTP server and doing something like this:

HELO fakedomain.com [domain to pretend to be sending from]
MAIL FROM:<[email protected]> [fake From: address]
RCPT TO:<[email protected]> [real destination address]
DATA
From: "I'm fake" <[email protected]> [fake From: name and address]
To: "Anything" <[email protected]> [has no effect, just shows in To: field]]
Subject: whatever
[any other headers you want to add]
[Body of message here.]
.
QUIT

Still, if you came up with that Eudora thing on your own, I think that's pretty good. Just check around to make sure you haven't reinvented the wheel before you go announcing it.