Email- is the most widely used resource. In 2010, more than 107 trillion e-mail messages moved through the net. It is useful, but also has drawbacks.
-it is not as formal as a printed letter.
-it is not as private as a letter.
-there are spams or junk mails that may be sent to your mail (they might contain viruses).
-information overload (too many e-mails for every worker to check).