If you know the name of the husband, it is proper etiquette to address the mailing envelope to "Mr. and Mrs. [his name here]". On the inner envelope the addressing can be much more informal, with a simple "John and Jane", etc.
Another Perspective
This is the twenty first century. Women have names and an existence apart from their husbands. An invitation can be addressed to Margaret and William Anderson. Most etiquette books are decades behind the times.
The way to address a shower invitation to a married women would be you address them by their full married name. Example: Mrs. Kate Bolton.Another PerspectiveThe best way to address a shower invitation to any woman is to simply use her name. This is the twenty first century. A shower invitation does not need to reflect a woman's marital status.To: Kate Bolton.
The address should read (an example): Dr. John Doe and Mayor Jane Doe.
Address it to Mr & Mrs. Jones. That is universally understood.
In this wonderful modern age you can simply write her name on the envelope. It doesn't need to label her as married, unmarried, engaged, solo, etc. For example: If the person's name is Giselle Renoir and you want to invite her to a party then simply address the envelope to Giselle Renoir at her address. If you want to invite her husband too then simply address it to Giselle and Pierre Renoir.
You address the envelope to the person and only put "X, Y and guest" on the invitation.
Invitations are usually written with the husband's name first. For example: "Mr. and Mrs. John Smith", "John and Mary Smith" or "Mr. John Smith and Mrs. Mary Smith". The latter is the correct form of address if the couple has divorced.
* Yes, the name and address on a wedding invitation should be centered on the envelope and your return address on the upper left.
If you are unaware whether a woman is married or not, use Ms. If it is a man, obviously, Mr. is used in all cases. so Ms. for a woman, and Mr. for a man.
hi. i need to sue my husband for trying to drown my fish.
The person who is sending the letter or other item. If it concerns something like an invitation and the address is different for the party the return address is still the person who is sending it. The party address would be inside the invitation.
The same way you would if her husband were still alive. Even though a woman's husband has passed, she still retains his name.
When you address a letter to a person in the military, you address it by rank. Colonel John Smith. First Sgt. Joe S. Miller. There may be 10,000 men on the base. There will probably be only one Colonel John Smith, Likewise, with First Sgt. Joe S. Miller. The object is to get the invitation to the right person out of 10,000 some of whom will have identical names.