I saw this question in that subreddit and I found it interesting. However, both top comments say opposite things
One says that they were "delivered to other ports and to ships via Packet Ship" , while the other answer says that "they largely didn't" and "That's why ships' captains had such insane amounts of authority over their crew".
How did ships communicate with the mainland then? I hope that I can find a good answer here. Thanks.
EDIT: I forgot tho add the link to the original post. http://www.reddit.com/r/explainlikeimfive/comments/2b1ilq/eli5_before_the_invention_of_radio_communication/
Those answers aren't mutually exclusive. Most major navies of the 19th century (i.e. France, Spain, the United States, and Great Britain) had squadrons posted overseas to protect their colonies and economic interests. For example, the United States posted the Mediterranean Squadron abroad to fight the Barbary pirates.
But given the distances involved and the relatively slow speed of sea travel (it took 30-40 days to cross the Atlantic in 1812), captains and squadron commanders enjoyed a great deal of autonomy. Now, most fleets usually had an attached sloop or other small vessel for carrying despatches (After Trafalgar, HMS Pickle carried the news of British victory home to Britain). Frigates could also be used to carry messages, although admirals generally preferred to use them as scouts and convoy escorts, rather than as long-range message carriers.
In other words, communications could occur between admiralties and far-off fleets. However, such communications were slow and resource-intensive.
In cases where ships could see the shore, a variety of signalling techniques could be used. Semaphore flags (i.e. wig-wag), signal flags, signalling guns, and hailing trumpets were all used for ship-to-ship and ship-to-shore communication.