James Wades WB8SIW in the latest issue of QNI Newsletter, December 2016, has written an interesting article "Some Observations Regarding Delayed Messages" on pages 2-3.
He points to the fact that during emergency exercises and for priority traffic, delivery time is often in the range of minutes, but at other times routine messages sometimes languish for days or weeks.
I have some QTC here which I originated and, months later, have not been delivered, as I've waited for a radio circuit to those stations in Europe and Africa, where a traffic circuit does not yet exist on CW.
These could have been sent via Email but the purpose was to offer practice in on-air traffic handling.
Naturally these messages were not important, and were just test greetings.
James Wades WB8SIW, RRI, offers useful proposals to improve this situation, including the creation of a new Bulk precedence which was covered in an earlier post on this forum, as well as a strict time restriction of 48-72 hours for delivery of routine messages before SVC back regarding non-delivery (and discontinuation of delivery attempts for Bulk messages).
He also proposes a "dead letter office" at state level for expired radiograms. This would be a volunteer, perhaps in rotation, which would check into nets and accept (R)outine radiograms that have reached the 48 hour time limit, and deliver these or SVC back the originating station.
This is a very good idea, and I will volunteer to do this in VK5 and for any other VK state that has no "DL" volunteer. If you could volunteer in your state to be a "DL Rep" please post here so we can pass you any messages reaching 48 hours without delivery.
Read his full article on the subject at http://qni-newsletter.net/