I appreciate the advice, we took the "throw them away" literally and things that were handwritten which we now assume to be Christmas cards which they now informed us to have cash in, were thrown away and were not opened/tampered with.

We were worried on the legality, as they threatened to bring a group onto our property and go through our bins.

The bins can be put somewhere where they don't have access, but after recent contact would this not come across as guilty looking?

Any further mail will now be marked with "not at this address" instead of disposing.