Editing Email client (section)

==References==
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<ref name="sill-security">{{harvnb|Sill|2003|p=353}}: "Like SMTP, POP3 is unencrypted. Unlike SMTP, however, it needs authentication: Users have to identify themselves and prove they're who they claim to be. Unfortunately, the authentication usually consists of presenting a username and a password known only to the user and the POP3 server. Because the POP3 dialogue is unencrypted, an eavesdropper can obtain a user's username and password and reuse them to access the user's mailbox. So, plain POP3 exposes the contents of the mail messages the user retrieves, and it exposes their username and password, which can then be reused by someone else.<br/>Wrapping the POP3 dialogue with transport-layer security such as SSL solves both of these problems. Because SSL-wrapped POP3 sessions are encrypted from beginning to end, no messages, usernames, or passwords are exposed in cleartext.<br/>The optional POP3 command, <code>APOP</code>, replaces the standard <code>USER/PASS</code> authentication with a challenge-response authentication mechanism. This solves the problem of the disclosure of reusable passwords, but does nothing to prevent eavesdroppers from reading users' mail messages as they're being retrieved."</ref>
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