What I've done for years: "generate" email addresses on the fly like zz-<portal>@mydomain.com and have a catchall rule for zz* in my main inbox. So if I get any mail or spam I can see where it originates from (and by doing this it I was able to point a portal to the fact that obviously they leaked mail addresses). By doing this I can block a single mail address.

This does break though when you are required to SEND with this email address.

Any services I can use this setup conveniently? Do I need my own mail server in this case?