First, let me thank you for this great service.
I have two questions to ask.
When refering to a person can we correctly say The Honourable Mr ....?
And what is the correct salutation (in letters) for a person addressed The Honourable (Mr)...?
Re: Honourable Mr?
The term "Honorable" is usually reserved for people like ambassadors. For most people it is sufficient to say "Mister".
'Honourable' is not used for ordinary people in British English. We use it for members of parliament, who call each other 'my honourable friend' when speaking in the British parliament.