@edavies @neil
There's a whole line of historical development of rules when intimation is effective.
Way back it was when someone became aware of it.
But it was too easy to say "I never saw/heard it", so you got personal service by an official giving it to you, or leaving it at your home.
Then the universal postal service was created, with regular & effective deliveries, so rules were created based on the expectation of such ("postal rule").
Now we're going through it again with e-delivery.