Bus-mounted mailbox

Buses follow predictable routes at predictable times.

The drivers who collect mail from fixed mailboxes do the same thing.

Why not mount a mailbox in the side of a bus ? The bus passes fixed points at known times. When it returns to the depot, its mail can be automatically unloaded and fed into the postal system.

In this way the latest postal collection would automatically be the time of the last bus to pass any particular point.

This service would supplement, not entirely supersede, existing fixed mail boxes. But it might cut down on the number of boxes needed and ensure more efficient deliveries.