I just came across a great New York Times piece on the mail service in the Victorian era. It's full of trivia: for example, did you know that in 1889 London, mail was delivered TWELVE TIMES A DAY? Read this:

In Victorian London, though service wasn't 24/7, it was close to 12/6. Home delivery routes would go by every house 12 times a day — yes, 12. In 1889, for example, the first delivery began about 7:30 a.m. and the last one at about 7:30 p.m. In major cities like Birmingham by the end of the century, home routes were run six times a day.

"In London, people complained if a letter didn't arrive in a couple of hours," said Catherine J. Golden, a professor of English at Skidmore College and author of "Posting It: The Victorian Revolution in Letter Writing" (2009).

And, not unlike us, most Victorian letter writers seemed more concerned about getting a rapid response than a long one. "Return of post" was an often-used phrase, requesting an immediate response, in time for the next scheduled delivery that day.