Dumb question about STDs

I know when we mail out the invitations, unmarried people can get addressed:
Mr. John Doe and Guest

What about the Save the Date?
Mr. John Doe and Guest ~or~
Mr. John Doe?

TIA

the STD are not really formal..at least they dont have to be..

on mine im just putting the names on them

and if its a family with kids i just put the doe family

the invitations is where you get more formal