Hi @newlightstudio - a phishing spam message usually comes from where a link goes to one URL but the text in the link shows another URL. Its a common tactic in tricking people to go to a very similar but "hacked" URL. Not much of an issue in Campaign as all links are usually rewritten for tracking purposes, but technically you can still misdirect people with the final URL.
Can you provide some more information on the URL that is throwing the spam error? Do you have any URLs where the <a> text is also a URL?