In uk.railway Mizter T twisted the electrons to say:
Of course even if
one omits the post town then it'll get through, especially if one is
posting from within that post town - e.g. London.)

It's amazing what parts of the address can be omitted, and still have the
item reach the destination! My personal favourite was the letter which
had (something like) the following on it :-

Mr & Mrs Smith
The house with the white(?) door opposite the church
$VILLAGE
Incorrect, albeit not massively, postcode ...
--
These opinions might not even be mine ...
Let alone connected with my employer ...