Letters he has put in post to North and South? It's left, if not right (10)

'not right' is the definition.
The definition and answer can be both human attributes as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'letters he has put in post to north and south? it's left' is the wordplay.
I cannot really understand how this works, but
'letters' could be 'es' (more than one E) and 'es' is found within the answer.
'he' could be 'ed' (short for edward) and 'ed' is present in the answer.
'north' could be 'n' (synonyms) and 'n' is found in the answer.
an anagram of 'and' is 'adn' which is located in the remaining letters.
'south?' could be 's' ('S' can be a synonym of 'south') and 's' is found within the answer.
A single letter 'h' remains which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).

'if' is the link.

Can you help me to learn more?