From Yoko Tawada's "The Art of Being Nonsynchronous":
Before digital technologies became a part of everyday life, the letter was considered one of the most important instruments for the transport of words. Even the telephone was unable to destroy the culture of letter writing. People who before had frequently written letters continued to do so to communicate things they preferred not to say on the telephone. The letter has developed its own for of distance that allows people to express things it might be difficult to say in person. This has less to do with inhibitions or politeness than with style. Writing a letter, you can borrow this or that turn of phrase from literary tradition to apply to your own life much more easily than on the phone. It wasn't until the advent of electronic communication that the culture of letter writing began to lose some of its dominance. There are many differences between an email and a letter on paper, but one in particular stands out, namely, the consciousness on the part of both sender and recipient of the distance between them. Even in the case of an overseas email, people tend to expect a response in the next few hours, as if the recipient's desk were in the same room. Mentioning the time difference or weather in an international email can already be interpreted as a personal, even romantic gesture. A handwritten letter, however, almost automatically announces the writer's absence to its recipient.