"Posting in all its branches" in the nineteenth century: travel, mail, other?

"Posting in all its branches" is a phrase I've seen a number of times in 19th century British sources.

A google search (regular and books) gives context mostly in reference to traveling or communication, but I can never tell exactly what is involved (it's understood by contemporary readers, of course, so no need to explain!). 'Posting' makes me think it might be mail or a telegram, but it be by coach or train or horse, I don't know what else (why mention all the branches if there are only two? I'm expecting a number of branches, just I don't know what all the possibilities could be).

Context:

• From google books - mostly located in advertisements for lodgings.
• In a biography about Jane Austen:

...it is only at very large establishments, or those in the most out-of-the-way districts where trains come not, that "posting in all its branches" forms part of the land lords boast

What I hope to find out is:

• What is being posted? Is it mail things like letters and packages, or is it travel?
• What are the branches? Does it mean train, carriage, horse, foot? Or does it mean local, national, international? Or does it mean letters/small packages or traveling individuals with luggage? or what?
• What would be advertised if the posting were not available in all branches? 'Limited posting' ?
• If it is not so literally meant, what does the phrase mean?
• What is time frame for this phrase being used? (Google ngrams, despite having ostensibly the same data source as books.google.com, gives -0- instances of the phrase, so I can't see a usage timeline).

The phrase in all its branches means by itself that they would deal with all types of what ever, in this case posting.

However, the word posting here meant the supplying of horses to the mail-coach, and by extension, the supplying of horses (and possibly carriages and drivers) to the general (presumably upper-class) customer.

From the Oxford dictionary

post [no object, with adverbial] historical: travel with relays of horses: we posted in an open carriage

From the novel A Popular Schoolgirl by Angela Brazil (1920)

In the long-ago days before railroads, the little hostelry had been a stopping-place for stage-coaches, and a wooden board still set forth that it supplied "Posting in all its branches." The landlord would no doubt have been much dismayed if any wag had entered and demanded a chaise and post-horses to drive to Gretna Green, and a shabby motor in his stable-yard showed that he marched with the times.

And to show what variety of conveyances "all its branches" might include, Google finds:

Posting in all its Branches, with careful and steady Drivers.
Posting in all its branches, including Ladies' Hacks, Pony Carts, etc.
He advertised posting in all its branches with carriages, waggonettes, dog carts, lorries etc, also a hearse.

ADDED IN EDIT:

Looking at the etymology of the word post, it derives from the Latin word positum. The word post in this sense is from the French word poste, meaning post or station, and when it was originally introduced into English in the 1500s, it meant both the mail and the system used for carrying mail, of traveling fast by replacing tired horses with fresh ones that were waiting for you at post stations. Apparently, by the 19th Century, the word posting had been generalized to mean all types of hiring horses and carriages.

The idiom here is actually the phrase “in all its branches”. It means every category under the thing identified. So the phrase “posting in all its branches” means all types of posting, that is, all types of postal service or mail delivery service.

Having all types of postal service available was an attractive feature of lodgings of the time. It is analogous to today's “free wifi”; if you stayed at such a place you would be well connected to the information network.

Try the Google Books search for this phrase and you will find it appears in the titles of many books, mostly nineteenth century vintage. In every case it refers to the work's completeness, or coverage of every category under the thing identified. Here, for example, is a summary of the first page of results that I received:

• The Tyburn Chronicle: Or, The Villainy Display'd In All Its Branches (1768)
• A treatise on the law of insurance in all its branches (1909)
• A treatise on the law of elections, in all its branches (1795)
• A treatise on the art of painting, in all its branches (1817)
• A practical treatise on the manufacture of paper in all its branches (1873)
• Comprehensive treatise on land surveying, comprising the theory and practice in all its branches (1812)
• Swimming in all its branches (1924)
• The new and complete Newgate calendar; or, Villany displayed in all its branches (1795)
• Bibliopegia, or, The art of bookbinding in all its branches (1835)
• Before the footlights and behind the scenes: a book about "the show business" in all its branches (1870)

Posting sometimes meant 'travelling by the mail-coach', the fastest form of travel till the railway. These coaches had specific contracts to transport the post between specified towns (along post-roads), and (obviously) they connected with each other, so the post-routes might be said to form a network or tree (if the words had been in use then), with a lot of branches.

Without context it's difficult to be sure, but that might be what you mean.