The Mailbox of Unsent Letters

Description
The Mailbox of Unsent Letters (often abbreviated to simply Unsent Letters) is a wildly popular thread on the YWP where users contribute supposedly unsent letters to the world. The posts typically follow a loose letter format, beginning with 'Dear ____' and ending with some sort of signature.

Ironically, the title of the thread often has no bearing on the content therein, as users often address their posts to each other and carry on conversations within the thread itself. This has occasionally created a stir within the Nano-verse. It has since been remedied.

The thread has proven to be wildly popular, and has been frequented by an estimated 85% of active users at one point or another. The thread is reset numerically after each Wipe, and the actual thread count is estimated to be around 70 or so.

History
The roots of Unsent Letters can be traced back to the grainy 'noir' days of the YWP, where 'air-it-out' or 'vent-your-feelings' Tumblr-style threads sprouted up like weeds in a graveyard. There was a lot of controversy over these threads, as users often took a passive-aggressive or simply aggressive attitude in posting whatever happened to aggravate them at the moment. This lead to the usual Internet dramatics, with subsequent closing of said threads.

Around the mid-point of 2014, a thread titled 'In Which We Send Unsent Letters' popped up, advertising itself as a place to put unaired thoughts and feeling towards events in one's life when said feelings could not be expressed IRL. Naturally, the thread exploded. As more and more users flocked to Unsent Letters, it grew more streamlined, with specific guidelines and etiquette added over time.

Currently, Unsent Letters is the most popular thread on Nano, and shows no signs of letting up.

Controversies

 * As the predecessors of Unsent Letters were not always wholesome and productive, i.e, "Things That Annoy You', some were initially skeptical of the thread, and aired negative feelings over its purpose elsewhere.
 * As Unsent Letters are supposed to be 'unsent', the practice of users addressing each other by name and conversing with each other within the thread has indeed been controversial. Some proposed removing the thread altogether, while others advocated for another thread focusing on 'sent letters'. Neither attempt has gained traction.
 * There have been vague reports of users identifying as veterans or old-timers critiquing the point of the thread, and reportedly floating the idea of having it censored by the Moderators. Most self-identified Nano veterans have been supportive of Unsent Letters, however, and as before, no censorship request was submitted.
 * Several posts have been particularly 'ranty' or revealing of personal events within users' lives, and there is a general consensus that such content is best reserved for somewhere off-site, as Unsent Letters was never intended to be a vent-style thread.

The Future
It would appear that Unsent Letters will continue to flourish as long as there is a YWP, and perhaps serve as a landmark to future generations of YWP users.