DEAR MISS MANNERS: One sends out an RSVP invitation with a specific deadline, and then, because of poor response, the hosts want to cancel. Obviously the regrets do not need to be notified. Those accepting the invitation should be notified.
A topic of debate within my household: Is the host under any obligation to notify those who did not respond?
GENTLE READER: Your implicit frustration with those who do not respond to invitations would normally find a sympathetic listener in Miss Manners.
But she finds herself wondering instead about the "poor response" you cite in justification of revoking an invitation that has been both issued and, in some cases, accepted. To these people the host owes an apology, an explanation and, ideally, a replacement invitation.
Given how many people are in the habit of attending events to which they did not respond, it would be wise to warn the non-responders as well, lest they appear on your doorstep expecting to be fed. In fact, you do not need to offer to feed them ever again.