Hey there, pjfarmer!
Thanks so much for using Apple Support Communities.
Being able to manage the phishing/spam messages you're receiving in your inbox is super important. We have some really great tools designed to help you accomplish exactly that. The first thing we'd recommend is utilizing the features built into Mail on macOS to mark mail as junk. This will help the Mail app improve the effectiveness of the junk mail filter going forward, each time you mark an item as junk: Reduce junk mail in Mail on Mac - Apple Support
If you've set up junk mail filters and they're not working as expected, we'd recommend that you work through the information in this article: If junk mail filters aren’t working in Mail on Mac - Apple Support
We hope this does the trick for you!
Cheers.