If you are being sent thousands of junk email messages, send them to Junk: Reduce junk mail in Mail on Mac - Apple Support.
If junk mail becomes out of control, abandon the email account. Be cautious when using your email address in public. Ideally, never divulge your email address, but if email recipients rudely divulge your email address to others without your consent, and it in turn becomes harvested by spam-bots, there is nothing you can do about that.
Apple offers a variety of tools to help you maintain control of your email addresses:
Add and manage email aliases for iCloud Mail on iCloud.com - Apple Support
Create unique, random email addresses with Hide My Email and iCloud+ - Apple Support