Wedding Etiquette; IF YOU CANCEL OR POSTPONE THE WEDDING

On 3:54 AM

You're supposed to return the engagement ring (now that's hilarious!!!)
You have to send back all the gifts with a brief explanation why it was canceled. (So don't use anything until you say, "I do".)
It's written that if a gift is engraved or personalized, you don't have to return it.
Don't speak poorly of your ex because somewhere down the line you might get back together. (Darsi added this one all by herself.)
You should inform out-of-town guests first so that they can change or cancel their travel and lodging arrangements.
If you're postponing your wedding, of course every guest has to be contacted. Etiquette pros say that you have to send another invitation with the new date.