Sending Ritual

The sending ritual is so ubiquitous across Ysireth that even low-arcane populations like Hymvari and wyl'Aeldvari know and use it. Developed fairly early in Ysireth's recorded history, before Duovari joined Aeldvari on the global stage, the sending ritual's original name and creator have long been lost to time.
The ritual's usefulness is twofold; firstly, it requires no personal arcana from the sender, and secondly, it can key the message to either a specific location or a specific individual. Its design uses minimal physical components that are easily found or cheaply acquired and takes advantage of ambient or environmental arcana to power its low magical needs.
The most common form of the ritual uses small mineral markers (stones, crystals, or even glass) to establish a tableau upon which a sender can then establish the destination of their message. Five of these markers are used, four of which are positioned in relation to each other to match four of the brightest stars in Ysireth's sky. To workaround the geometric accuracy required, the ritual creator developed an extremely short invocation to automatically align the four markers with respect to the constellations.
The fifth marker is used to indicate the recipient, be it an individual or a location. The fifth marker is placed upon a piece of paper (parchment, vellum, stone--even a leaf may suffice) that depicts the destination's signature. The signature, in turn, is either scribed as a memorized glyph if a static location--in much the same way that major settlements have unique teleportation circles that a sorcerer can memorize in order to easily travel to them--or as a personal glyph that represents a person. A personal glyph can be created by the sender independently or given by the future recipient; a single person may have many personal glyphs that can indicate them for the purposes of the sending ritual.
It is worth noting that these personal glyphs are useless outside of the magic of the sending ritual. It is unknown how the ritual's creator safeguarded these symbols and prevented any method of tracing a person (or a sent missive), but the magic has remained intact through nearly a hundred thousand years of recorded history.
The last step of the ritual is a second simple invocation to send a missive (a small paper-like object, nothing larger or heavier than would fit in a reasonably-sized thin envelope) that is placed overtop the fifth marker than sits atop the recipient's signature.
A variant of the usual sending ritual, used when materials are handy and secrecy is preferred, uses a second set of markers to establish the signature glyph instead of committing it to paper and risking it being seen or taken. These markers may be extremely small pebbles, salt crystals, sand, flour, or powdered crystal that forms the glyph instead of writing it, enabling the materials to be scattered immediately after the missive is sent. Some people who prefer this version of the ritual will keep a small pouch of gemstone shards for this use, along with five larger crystal markers for the recipient and stars.
Even for small family homes, it's possible to enchant a written sigil to act as a landing pad for missives sent using that sigil as a recipient, essentially making an arcane mailbox.