Mr. John Doe and Dr. Joanna Doe
Mr. and Dr. Last Name.
Address on envelope to a doctor: Dr. John Doe is the general form.
The envelope should read: Mr. John Doe & Dr. Jane Doe. If you don't know her first name then put: Mr. & Dr. John Doe.
Dear Mr. (name) and Mrs (name)
The address should read (an example): Dr. John Doe and Mayor Jane Doe.
Senior Doctor first if it is a medical reason or unmarried, Man first if it is a married couple.
Same as to anybody else. Put the name and address of the person clearly in the center of the envelope.
Senator John Doe, MD
Whichever is the highest qualification, which would be a doctor as a mayor is elected not qualified.
When address to a doctor it should appear as: Dr. John Doe or John Doe, MD.
When addressing an envelope to the wife of a doctor who is not a doctor herself then and he is Dr. John Doe, then address the envelope to her as Mrs. John Doe or Ms. (Mrs.) Jane Doe.
The proper way to address an envelope to a doctor office is to first input the name of the clinic. On the second line you can insert in care of or C/O with the doctor's name. On the third and fourth line you can insert the address, city, and zip code. Include any suite or floor numbers of the doctor's office on the third line.
That would be: "Dr. John and Mrs. Jane Whomsoever".