On Sun, 25 Apr 2004, Lars Dybdahl wrote:
One of the easiest way to see, if an e-mail is spam, is when the e-mail
has a @hotmail.com address but wasn't sent through hotmail's
mailservers... most good spamfilters know this one, so you just should
not send an e-mail from a business internet connection with @hotmail.com
as sender e-mail address. This is not related to SPF.
One of my spam filters rejects all mail claiming to be from hotmail.com
that doesn't have an "X-Originating-IP" header. Any mail that's really
from hotmail will have that header line.