Post Office Protocol version 3 (POP3) is a protocol for retrieving messages from an email server. In our example, when Jennifer logs in to read messages, her email (client) program may use POP3 to communicate with Surewest’s email server to retrieve messages.
A typical POP3 client downloads all the messages from an email server. This is fine if the user only uses a single machine for checking email. However, if this user uses different machines (home, office, mobile) to check messages, then each message can only be stored on one single machine.
Although it is possible to tell an email client program (such as Outlook and Thunderbird) not to remove messages from an email server, POP3 has no mechanism to mark which message is read, and which one is unread. Consequently, it is difficult to manage messages that are stored on an email server using POP3.
This sounds like we need a better mechanism to manage messages.