The previous occupants of our house moved out in December, we moved in in April. There has been quite a large amount of post for them, including vehicle tax forms, bank statements, mobile phone statements. Twice the people have come to our door and asked for us to put their mail through next-door-but-one's letterbox (friends who will forward it to them). I thought this was reasonable, but DH is concerned that they are still using this address for important correspondence, and could maybe use the letters as proof of address to obtain credit. He also thinks they still have a key to the house and were accessing it to collect their mail whilst empty as there was very little on the mat when we moved in. The lady (former occupant) came yesterday and said the postlady is still putting mail addresses to them in next-door-but-one's letterbox even though it has our address on it. DH wants to complain to Royal Mail as he thinks this is not allowed.
So, am I a complete arse to stick all this mail back in the post box as "not known" and complain to Royal Mail? Or would I be a mug to let them get away with it?