One step beyond Mojave...
The Mail app in macOS Catalina has been updated to allow you to easily block and unsubscribe to emails. It can block all email from specified senders and move their messages directly to the trash.
When you block mail from a specific sender, those emails will be automatically moved into the trash. I’ve found this to be a great time-saver in my never-ending battle with phishing and spam.
https://eshop.macsales.com/blog/54368-catalina-quick-tip-block-mute-and-unsubscribe-from-email/
In Mojave use Mail Rules, or what works for me is $15 spamcop.net reporting to get the spammer shut down util they remove you from their mailing list.