The etiquette faux pas we hear perhaps the most complaints about is a failure on the part of guests to RSVP to their host or hosts. Barbecues, office parties, weddings—you name it, hosts are being left to wonder if anyone will be in attendance. No matter how you receive an invitation, it's critical to let your host know if you'll be accepting...or not. That's right, with the sole exception of a "regrets only" invitation, it's just as important to let your host know if you can't attend as it is to let him or her know if you can. Here are some typical ways invitations are extended and how to RSVP:
Call and make sure to give your response in person—an answering machine can be unreliable.
Hit the REPLY button
Follow the directions to reply, and don't stress out over trumping another guest's witty response. If you opt for "maybe," make sure you follow up with your final answer.
You can respond right away, or if you prefer not to be put on the spot, say, "Let me check my calendar and get right back to you." Just be sure you do exactly that!
Fill in the card and return it in the enclosed envelope. Reply right away or by the date indicated.
Send a prompt handwritten reply to the host at the address on the envelope.
You only need to reply if you can't go. If your host doesn't hear from you, he's expecting you to be there.