Depends on whether you wish to be kind, or offensive, right?
Mr and Mrs would be proper. Attorneys are typical written to as Mister.
addressing attorney and wife
The Honorable (similar to a judge)
Dear Counselors:
Rabbi and Mrs.
To whom it may concern
A proper salutation for greeting the president of a business is "Dear Mr. President". To conclude a letter, the proper word is "Sincerely" and a the name of the writer.
"Dear" is what people use it nowadays.
Dear Mrs Ambassador..
yes
vmrs
The proper salutation for a letter to someone with an MDiv degree would be "Reverend" if they are ordained as a minister. If they are not ordained, you can address them as "Mr." or "Ms." followed by their last name.