Is it possible to spoof the From: field in Outlook?

"Try the following commands (type them into a command prompt and press Enter after each one):

telnet smtp.mailserver.com 25
HELO QA
MAIL FROM:yourid@mailserver.com
RCPT TO:yourid@mailserver.com
DATA
Subject:test mail
This a test mail
.

The last command is a dot (.), to end the email. Replace ""mailserver.com"" with the URL of your mail server, of course.

If you see a message like the following, then it means you've successfully spoofed the sender email:

250 2.0.0 qA28jUNa098936 Message accepted for delivery

Source: http://automatethebox.blogspot.in/2012/11/email-spoofing-how-to-spoof-email.html"