For special gatherings, an RSVP is often necessary. This allows the party hosts to have a solid idea of how many people will be in attendance so they can assess their expenses. Often, hosts may choose to invite more people than they have allotted for, with the expectation that some will not be in attendance. If the response is mostly positive, it may be necessary for hosts to uninvite some people. Rather than taking this personally, there is a gracious way to respond to being uninvited to such an event.
Send confirmation that you know you have been uninvited. If your feelings are hurt, it may be too difficult to talk to the party hosts over the phone, so you may choose instead to send a letter or e-mail notifying them that you got the message and will not be attending the event. This is important for their records and budget.
Offer your best wishes and thoughts to the party hosts. In the confirmation letter or e-mail you send, let them know that you wish the host or hosts only the best. This will make you seem like the bigger person, while allowing them to enjoy the special day without feeling guilt over uninviting you.
Do not feel obligated to send a gift to the party hosts or guest of honour. Because you were invited to the event, it would have been polite to bring a gift unless otherwise noted on the invitation. However, since you were uninvited, there is no need to give a gift. If you have already purchased one, you can still send it if you choose, though you may also return it or keep it for yourself.
Consider whether you should invite the hosts to your own future events. If there are no hard feelings, you should feel free to invite them to let them know that you are not bearing a grudge. However, if you feel that seeing them again may stir up emotions between you and the party hosts, you should avoid making yourself or them feel uncomfortable.
Do not show up regardless of having originally been invited. This is not only tacky, it can lead to a potential conflict at the event.