Dave Plowman wrote:

Or rather they seem to be called letterbox plates these days.

My PVC door and side-panels came with fairly crappy "aluminium" flaps
(same inside and out) which didn't match the rest of the chrome door
furniture. It didn't take a dopey delivery driver long to force
something too large into and break off one of the flaps ... temporarily
I reversed the inside and outside flaps.

It took me ages to find a good, larger replacement, but not too large to
fit the frame ...the the internet seems to be full of cheap ****ty
letterboxes.

Eventually got a decent PVD chrome plated one, to make it draught-proof
it has springs stronger than Arkwright's till, so the postie probably
hates it, charity collection bags tend to end up scrumpled between the
two flaps.