Short for Authenticated Post Office Protocol,
it is similar to the POP
protocol except that APOP enables your password
to be encrypted while being transmitted over the
network. Using POP mail, when you authenticate your
username and password in your e-mail client, your
password is sent over the network in plain text. If
your e-mail client uses APOP, then the password is encrypted while being
transmitted. APOP prevents hackers from seeing your
password information with sniffer programs.