This sounds like a naive question, but I'm studying the subject of registered mail and what it is. Most examples of mail I see, like from the States, transits a "registry division": if dispatching, transit and arrival post offices have to log all registered mail that they handle what then is the role of these specific 'divisions' along the way?
By extension, if there is a registered letter that does not have a registry division transit, but it does have other post office transits/arrival/dispatch marks, can we assume it was properly handled as registered mail?
Registry Division typically refers to the department within a larger post office which handles only registered mails. For small post offices, the postmaster or a window clerk performs the necessary functions.
Registered mail usually implies that there is some manner of valuable present, so it's handling and processing is strictly controlled. As registered matter moves from one post office to another en route to its destination, there are signatures obtained to provide a chain of custody.
Registered mail with ordinary postal markings, date stamps, cancellations of stamps, etc., but with additional notations like "REGISTERED" stamped or written on the envelope with an identification number, should be considered to have gone by registered mail, even if there is no "Registry Division" marking present.
After about 1900, the Post Office Department issued specific date stamp devises with the words "REGISTERED" or "REG. DIV" in a double circle date stamp, so mail after that time almost always will have such a marking. After 1911, the original post office was required to strike the back of an envelope along the flap to prove they had examined the envelope and assured that it was properly sealed. This registered device was often used for this purpose.
https://stampsmarter.org/features/N...RegHome.html will take you to the Registered U.S.A. census with many examples of registered covers. Under the sub heading "ebook downloads" you will find "REGISTERED U.S.A." available as a free download. This census is one of my projects and I am the author of the book. Both should give you useful information in your quest to learn more about our shared interest in registered mail. Have just a minute to post now but look forward to more conversations about out shared subject. Always happy to share info. "Information shared is history saved." Ryss
As to registered mail between the USA and other countries, there were various registry exchange offices where USA registered mail was sent and from there on to the registry systems of other postal system. Likewise incoming to the USA registered matter was received at these offices for distribution within the USA.