Take John Smith as a sample name. If you are sure he is married, your best option is
Mr. & Mrs. John Smith
If this is for a reunion-type event, and you are not sure if the alum is married:
Mr. John Smith & Guest
For an alum who is a woman, if you don't know her new last name, you might try
Ms. Jessica Smith & Spouse (or & Guest)
When addressing a business envelope where the husband is Mr. and the wife is Dr., the proper way to format the names is to list the titles in alphabetical order. Therefore, you would address the envelope as "Dr. and Mr. [Last Name]." For example: "Dr. and Mr. Smith." This shows respect for both titles.
Say there last name was "Smith" you would write Mr. and Mrs. Smith.
A baronet is addressed as "Sir", and his wife as "Lady". Exactly how to address the envelope is a little dicey , but "Sir John Doe and Lady Doe" would be acceptable, I would think.
Mr. & Mrs. <lastname>
I think it would be proper to address the two married PhDs as Drs. John & Jane Doe
Dr. & Mrs. John Smith
Addressing a husband and wife who are both Reverends: Reverends John & Jane Doe.
Dr. Mary Smith and Mr. James Doe
How about Mr. and Mrs.
if addressing an envelope it would be to the Reverend Canon or just Canon. His wife would be Mrs... The oral address would be Canon, and his wife Mrs.....
Type your answer here... Mr. and Mrs. Mark Henderson
Drs. _______ and ________ Smith