If You're The Guest

For Post, the biggest etiquette rule for a guest to keep in mind is to respect the RSVP by date. "This is similar to any situation at work: You wouldn't ignore a deadline set by your boss or coworker," says Post. If you're not in the position to give a definite answer just yet, mention that you got the invitation and need to check in with your schedule. "Try your best to give the host an answer really quickly, and do it in the fashion the host has requested — whether it's by post, phone call, email, or text."