Dr. and Mrs. John Smith, or Dr. John Smith and Mrs. Ann Smith. John and Ann Smith is also appropriate, and might be the best choice in this situation.
If you were sending a letter to John Smith, MD - you could address the letter to Dr. Smith.
The proper way to address a letter to a married couple with a suffix at the end of the name is to adopt the traditional rule of keeping the man's first and last name together. Mary and John Smith This is the proper way to address a married couple when using this format. So it follows that: Mary and John Smith Jr. Mary and John Smith III Mary and John Smith, Esq. would also be the proper outline.
You would address the letter to John Smith III. This is the proper way to denote that he is the third person in his family line with the name John Smith.
If the letter/invitation is primarily to the reverend but also her husband: Rev. Mary Smith and Mr. John Smith If the letter/invitation is primarily to the husband but includes the wife: Mr. John Smith and Rev. Mary Smith If it is strictly a business letter and not church related: Mr. & Mrs. John Smith
A PhD is a doctor. You address a letter to him Dr. John Smith. If he is married you address it Dr. John and Jane Smith. If she has the PhD, you address it John and Dr Sue Smith. If both have their PhD's you address it Drs, Henry and Jane Smith.
* Proper address for a General and his wife: General & Mrs. John Smith.
The proper way to address that letter would be "Mr. and Mrs. John Doe."
Best I can do on this one: Since the person is not officially an ambassador yet, you would address the letter as follows: Dr. John Smith Ambassador Designate to Oklahoma <<at his present address>> In the greeting of the letter, refer to him by his present title: Dear Dr. Smith, etc. In the opening of the letter, it is always proper to congradulate him on his appointment. After his becomes official, then you would address the letter to: Honorable Ambassador John Smith Embassy of the United States 123 Any Street Omro, Oklahoma 12345 and in that greeting: Dear Honorable Ambassador Smith...
The salutation used for the envelope address can be either Dr. John Smith and Dr. Jane Smith, or Drs. John and Jane Smith. If you are writing a letter to both doctors, then he greeting in your letter can be Dear Drs. Smith.
Dear Mr. John and Rev. Sally Smith,
dr Mary smith would be the correct way
For the salutation you would write: Dear Mr. (or Mrs. or Ms.) Smith On the envelope you would address it as: The Honorable John (or Jane) Smith American Consul General Address