Penfriend is “a person with whom one becomes friendly by exchanging letters, especially someone in a foreign country whom one has never met”, as Google defines it. That it’s an old way to communicate with people around the world but nowadays you can receive the letter or the postcard much faster than before. From there you can also make really good friends! Postcrossing is a project that allows anyone to send and receive postcards from all over the world: “The idea is simple: for each postcard you send, you will receive one back from a random postcrosser from somewhere in the world.”- it says.
You can find more information about it if you click on the photo above this text.
So to answer the question: is pen and cyber friends reliable? Carefully, it may not just be reliable but also really useful!