Two things to try:
1. Go to Mail > Preferences > Junk Mail and select Blocked. Enter the offending email address in the field. Then, click Junk Mail Behaviors and select "Perform custom actions". Click Advanced and go through the options.
2. Go to Mail > Preferences > Rules. Set a new rule and select your options. For me, I have most of them set to Delete Immediately so I don't see spam at all, but you may have another preference.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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