A bit late on this, and from the US perspective, but I’ve always just crossed out my “proper” address on the envelope, leaving the recipient name intact, and put it in the outgoing mail slot or in the mail box with the flag up. The mail man takes it away — no idea what he does with it (destroys, returns, takes home, etc.), but it’s not my problem anymore and I’ve complied with the law here.

Regards,

Jeremy