|There are few things you can do, none of which is guaranteed & all of which are a pain in the butt. |
1)Setup filters in your email client.
2) Trace the email through the headers to find the unsecured relay & report it to the server owner. I've been lucky enough to have a few closed.
3) Create a new email address & abandon the current one. That's probably the easiest & best idea.
How do you know when a politician is lying? His mouth is moving.