For those of you who did STD postcards on Vistaprint did you mail them as a postcard or put them in an envelope to mail? If you mailed them directly as a postcard how did you address them? Were you able to run them through your printer to address them? Did you write the addresses by hand? I have been told that using labels is a no-no so I am leaning towards sticking mine in an envelope that I can run through my printer to address.