The PO only needs an accurate complete address, right down to apartment or suite number and ZIP+4. Names don't mean squat to them. After it gets to the right address (house or office) then the name becomes important, but only if there's more than one person with the same first name.
It is important for you to use a last name when mailing a card. This is because people has similar first names and it might go to the wrong address if it is just in one name. Make sure that the address in correct before mailing.