There are some real nice and helpful email report in your Microsoft 365 Security console if you haven’t taken a look recently. You can pull them up by visiting:
as shown above. Then selecting Email & collaboration reports on the right.
The one I really like is the Mailflow status summary which you can drill into further by clicking on the heading or selecting the View details button.
If you then select the Funnel option across the top as shown, you get an idea of the number of bad emails that are being caught by each stage of the filtering process, from top (total in) to bottom (remaining out).
However, the report I love is the one you get when you select the Tech view as shown above. Why? Because this one even shows you results from DMARC as highlighted.
Many also allow you to Create schedule as shown above,
that allows you to email the reports regularly.
Keep an eye on the reporting areas of your tenant, as they are rapidly improving and expanding!