Resolved Question: How do I block a specific sender of mail from sending me physical mail to my address (not email- real mail)?

A particular “religious” organization keeps sending recruitment mail to my address which I am not interested in or affiliated with in any way. I receive upwards of 5-6 pieces of physical mail a day from them! I have emailed them to ask to stop which they said they would (over a year ago) but they have not, and my continued email correspondence to them is now ignored. How can I block their bulk mail? Just for clarity again, I’m referring to physical mail in my home mailbox not email spam.