Email spam that says it isn't spam is still spam. Notations in email that certify the email is virus free doesn't make the email virus free. One shouldn't rely on any such claim or text on emails, even if it's legit and not spoofed. Treat all email as potential security risks until proven otherwise. Don't trust someone else's AV to do the job either. I''ve received infected emails (that my AV caught) from people who swore their AV was up to date. Trust your own security practices first and then perhaps your AV, but no one's else's.