If you're a #postmaster (e-mail admin) and struggle with incoming spam, I suggest you increase the SpamAssassin score of all e-mails coming from Gmail, Outlook, Yahoo, Yandex and other popular free mail services.
This is because these services usually have excellent reputation and always pass SPF/DMARC/DKIM checks.
The point is to neuter these score reductions because of compliance, so that if a message contains suspicious words that SpamAssassin dislikes, it's going to get flagged as spam.
I for example set the score increase to 4 for messages coming from these free services, and my SpamAssassin filter starts flagging e-mail as suspicious at 5, and as spam at 8.
Because the negative scores from these DKIM, SPF and DMARC policies will deduct points from the 4, e-mails will only get flagged as suspicious if they contain obvious spammer techniques such as all-caps subjects, or mention viagra, or money.