Spee & D Courier Service, Inc.

Long-distance communication is still not practical in New Z'hrat. Due to the fact that magically controlling what others see or hear is considered mind magic and was outlawed for large portions of Z'hratian history, development of telepathy and mass or distant communication spells have been almost entirely frozen. Telepathy  is possible to only a few elite wizards, and it is difficult to perform over long distances even to them. Technological means of communication are still in development, with the exception of the radio, but the airwaves are owned and strictly controlled by Brimstone's League of Visual and Performing Artists  (see: Gehenna Towers )
Therefore, short of paying for a radio shoutout and hoping that the person they're talking to is tuned in at the time, hiring a courier service is still the fastest, most secure, and most practical way for the average citizen to ensure a message reaches its' destination.

Utility

Everyone uses courier services, whether that be to send letters to loved ones in a different neighborhood or to send reports and memos to a different office building. Mail fraud and scams are fairly common, but Spee & D takes no responsibility for the content of any letter or package sent through their service.

Social Impact

Being able to communicate across neighborhoods was a huge boon in the early days when the districts were not yet connected to each other and road travel was still very dangerous. In the modern era, thanks to their use by guilds and businesses, the courier services are one of the most important pillars of society, despite not being guilded.

Inventor(s)

Speigel and Dreech Jenkins were twin goblin brothers who founded the company in 202. Their experiences as early members of The Sentinels of Thunder  who protected the roads illuminated the need for a courier service to cut down on dangerous travel for civilians. The company is still owned and operated by their descendants.

Access & Availability

Courier services are extremely common, and send messages for individuals and guilds alike.

Complexity

Fairly straightforward. Spee & D Inc. has an arrangement with the Transit Alliance to use their high speed rails, but couriers are also known to use motorcarriages or flying mounts like hawks or griffins, depending on the distance.

Discovery

Founded in Year 202 by two goblin brothers, Spee & D is still widely regarded as the best courier service to use.