You can instantly reply to a message. Many don't even have a computer. Not everyone checks their E-mail regularly. Computers have been known to swallow some messages whole before they're ever received. Minimal threats of privacy invasion.
Hackers can and do find ways to read E-mail.
Even with these objections, E-mail's disadvantages are so small. Around the industry, growth is the buzzword for E-mail's future. The Electronic Messaging Association estimates that by the year 2000, more than 108 million users will be sending 6.9 trillion messages annually. And some of them might be yours. In the future, most of us will have two addresses, one where we receive our postal mail and one where we receive our E-mail.