synonyms with 'dear'

[Offroad]

Please, teachers,

what words would be synonyms with 'dear' on these cases:

a) whether I am writing/talking to known people:

Dear Sir.

b) whether I am writing/talking to beloved or related people:

Dear Jane...
Dear son...

Thank you very much

[IvanV]

Well, both of them mean the same - dear - exactly as it's written. Although, you'd omit Dear when writing an informal letter, such would be the case when writing a letter to a son, or a brother, for example. It's not a matter of the meaning itself in formal letters, more that is just a formality.

I.