Address it to Mr. and Mrs. followed by the man's initials and then the surname.
More Modern Perspective
Addressing a letter to a married couple in the man's name although traditionally and historically accepted, it is no longer universally accepted since it originated in times when a married couple was viewed as one entity and that one entity was the husband. Women now have their own independent legal status in most modern cultures. In fact, in more modern cultures one might ask the question as how do you address a letter to a married couplerather than to a husband and his wife.
It is important to know the preferences of the couple but the following methods of address are acceptable and you can read this and more at the related link:
Married, she uses her husband's name socially
Mr. and Mrs. John Kelly
Married, she prefers Ms.
Mr. John Kelly and Ms. Jane Kelly
Ms. Jane Kelly and Mr. John Kelly
*Do not link Ms. to the husband's name:
Mr. and Ms.John Kelly is incorrect
Married, informal address
Jane and John Kelly
John and Jane Kelly
Married, she uses maiden name
Mr. John Kelly and Ms. Jane Johnson
Ms. Jane Johnson and Mr. John Kelly
If you can't fit the names on one line:
Mr. John Kelly
and Ms. Jane Johnson
*Note the indent, either name may be used first
Dear Mrs......
You can address a retired colonel as "Colonel (Last Name)" and his wife as "Mrs. (Last Name)" or "Colonel (Last Name) and Mrs. (Last Name)" in the salutation of a letter.
Address the man in the same manner as if his wife were not a dentist.
To address a man and wife when he is a Jr would be:Mr. and Mrs. Mitchell O. Smith, Jr.When wife's name is unknown:Mitchell O. Smith, Jr. and wifeInformal:Mary and Mitchell Smith
To the wife only, just as Mrs. She has no title of her own.
The best way to address your letter to a Minister is to Reverend and Mrs. _______
Govenor and Mrs. Beebe
What is the proper etiquette to addressing a Reverend in a letter?
To;The Reverend and Mrs (Insert name)
Captain and Mrs.....
men
There is no formality when a wife writes a letter as to whether her husband or her own name comes first. Generally it is the man and woman if the letter is being sent to another man and if the letter is written more to the wife of the person you are sending it too then you can put your own name first. It is strictly your choice.
You would use the first name of the husband and the first name of the wife. This is how you address a Japanese married couple through a letter.