I believe it depends on the purpose of the correspondence. For social purposes, Emily Post says Sarah Ann Jones who marries John Smith becomes Sarah Jones Smith (Mrs. John Smith). (That's how my mother -- a very proper lady -- always signed my report cards!) For genealogical purposes, I think the custom is to use just the woman's birth name e.g. Sarah Ann Jones married to John Smith. I notice that my kids' birth certificates carry only mother's maiden name. (And we were very much married, thank you very much.) Candace McCarthy King