Sure, in addition to this though. IP reputation comes from spamhaus.org and the like and implemented in spamassassin or something similar, at SMTP(ish) level.
What you're talking about there is SPF/DKIM etc, which is an anti-spam measure but not IP reputation :)
What you're talking about there is SPF/DKIM etc, which is an anti-spam measure but not IP reputation :)