Email is both paperless and can be saved easily. Email is efficient, convenient and can be completed in isolation. Email is cheap and sometimes free. Email is very effective for a time manager. Email can be used for a brief communication.
Email makes it easier for people, in and out of business, to keep in touch.
Mailing lists are also popluar in email today, they can be good and bad, but if used properly they can be very helpful in mailing you updated information without you having to find the information yourself. One draw back is the fact that any information on the internet could be false and needs to be verified with one or more sorces before it can be taken as truth. As with any new technology, email has a bad side as well. Email may lead to communication slavery. The convenience of email encourages personal use.