A Month of Letters (LetterMo) was started in 2012. The letters/postcards should be sent every postal day in February. They can be handwritten, or typed. There are achievements for different styles. The site came under new administration and moderation in 2018. The site is still up and running in 2019.
InCoWriMo was started in 2013, and wanted handwritten letters/postcards to be written every day in February. However, in 2016, there was no update to this site (no notice of this beforehand). The List of names supposedly contacted by those running the site are mainly fountain pen executives and other stationery associates, plus a few celebrities. On 29th January 2018, the site was finally updated with an address exchange page, and again on 28th January 2019
InCoWriMo-2017 was born out of the non-event in 2016, and has been been managed by one of the InCoWriMo participants of previous years with a passion for snail mail. It had been updated for the 2018, and again for 2019 - a handwritten letter every day incowrimo-2019.org
What do you write in a first letter?
The first letter can be quite daunting. I used to write something akin to a CV mentioning some hobbies (all about me)- but now have changed what I first write. Perhaps I have always wanted to visit the area you live in or have already been. Perhaps the name of your street evokes some memory or connection. Perhaps I have a relative or friend shares your first name and then there is a little anecdote to tell (how they had posters of Tom Jones, Sean Connery and/or other music/film stars, etc – your reply could be, “It wasn’t Tom Jones on my wall but David Bowie..”).. The old fail-safe – the weather (have you been affected by the storm/tornado…?). I even imagine we are friends already.
How should I date my letters?
In the UK, the date is written day-month-year, but in the US, the date is written month-day-year. It can be confusing if only the numbers are used for the month, so as not to puzzle people, please write the month out using letters (either abbreviated or in full).
How should I start the letter?
One way is to start with Dear [person's name]. You can also use Hi, Hello, or just use the person's name.
How should I end the letter?
I use Best Wishes, but there are a wide range of phrases possible. The person running InCoWriMo-2019 wrote a blogpost mentioning Emily Post’s 1922 book on Etiquette, where there is a section on this matter.