Moving messages from place to place in the 10th Age can be dangerous and is certainly time-consuming. People rarely have the time to carry their messages directly to the person they want to speak to; that's one of the reasons why messages exist in the first place! Otherwise, you could find who you were interested in talking to and just go and talk to them.
This has led to the growth of a sort of "industry" if you will of viatores and heralds who, for a sum, will serve as message-bearers to distant lands. Sometimes viatores band together to form small guilds or mercantile interests and they generally have contacts with local shipping in order to find themselves cheap rides on boats, which are the fastest method of travel.
Viatores are common in the more sensible kingdoms of Atva-Arunia. The empire has a great number of them, but they can be found in Dorlan, the Three Kingdoms, the Vales, Weyland, Stonemark, Claulan, Llyris, Anarea, the Wilderlund, etc. All elvish kingdoms maintain their own special types of message-bearers who will be discussed later. Dwarves have followed suite with the mannish practice and mercenary viatores or letter-delivery folk can be found throughout the Arinnfal and other dwarf-dominated regions.
People who choose to be viatores range in motivation from the purely mercenary to those who seek the adventure of travel. Indeed, many viatores are actually simply adventurers paid to bring messages back and forth between distant regions. Of course, they are generally more reliable than the common adventurer, since most adventurers would forget they were even carrying anything important and let the letter or book or what-have-you fall by the wayside. Some kingdoms may endorse official viatores; in the empire, one is required to get a seal of approval from the Sacred Heralds which demonstrates that you are a reliable carrier.
Elven messengers are very often mages and grammaticians who use the Silver Road to travel between the kingdoms of the elves. Since the wind elvish custom of the cross-cultural paidea teachings unites all wind elves and requires constant exchange of teachers and ideas, these selfsame tutors are used to bear messages from one elven lord to the next. Use of the Silver Road cuts out most of the time that would be taken by travel, causing news to travel very fast indeed amongst the elves.
Sacred Heralds are a different proposition altogether. While they serve much the same function as viatores, they predate any secular messenger service. A private cult of women who serve Vaela the Roadwarden, to touch or harm a Sacred Herald is tantamount to gross impiety. They themselves are sacral, protected by the love of their Goddess. Hiring a Sacred Herald to bear your words is not cheap: they are well-outfitted and must perforce charge a hefty fee. Indeed, traditionally the emperor alone uses the Heralds to bear his word, but in this modern day it is possible for anyone to engage a Herald to carry messages.
They have a network of waystations throughout Arunia where they can change horses, and they deliver messages without fail; even an orc or an ogre knows better than to risk the hatred of Vaela by attacking her chosen children. For this reason, Heralds always wear bright identifiable colors with the Shield and Staff of Vaela clearly displayed upon them.
So, if you're looking to send a message to someone in Arunia, first you should check with the local viatores guild (if there is one) and only after that look for mercenary viatores who will bear your message. The Sacred Heralds remain an (expensive) option for those who simply cannot wait (Sacred Heralds are said to be much faster than most viatores) and who know the nature of their message makes it of extreme importance. Indeed, Sacred Heralds alone are sworn not to read the contents of your letters (though to be fair, most viatores, like most people in Arunia, are illiterate.)