Barb,
I did labels for both the guest's name and the return address. If the etiquette police want to come arrest me then so be it. Feel free to use labels if you so choose.
Good Luck!
She asked it it was PROPER. Like it or not, it never has been and still isn't proper. Just because you used labels doesn't suddenly make them "proper". I'm not the etiquette police, as I certainly didn't tell her she can't or shouldn't. She can do whatever she likes. I merely answered her question.
You should never use labels, if you want to be proper.
A handwritten invitation is classy and beautiful. With all the new ways of doing things, its nice to stay with tradition.