How do digest readers know their posts are successful?
ListProc doesn’t currently provide a mechanism for digest subscribers to receive immediate confirmation that their message went through. The four subscriber mail methods (ack, noack, digest, and postpone) are mutually exclusive. You can make sure that subscribers receive bounced messages by setting DONT-FORWARD-REJECTS. If you would also like the owners to be notified when messages are rejected, you should include CCIGNORE in their preferences.