First, email is universal. Anybody with an email address can reach anybody else with an email address, no matter which systems the senders and receivers are on. Second, email is still the best medium for many private, short- to medium-length messages, particularly when the exchange is limited to two people. Unlike with microblogs or messaging, for instance, midsize messages are easy to compose and easy to read on email. Third, email's non-instantaneous nature is an advantage when used properly. Email lets senders compose substantial messages in private and on their own schedule, and it lets recipients read those messages at their leisure.