What does POP3 do in its default state regarding username and password information?

In its default state, POP3 (Post Office Protocol version 3) sends username and password information in plain text. This means that when a client connects to the mail server to retrieve emails, the credentials are transmitted without any form of encryption. As a result, anyone monitoring the network traffic can easily capture and read this sensitive information, which poses significant security risks. Consequently, it's generally recommended to use a more secure protocol, such as POP3 over SSL/TLS (known as POP3S), which encrypts the connection and provides a much higher level of security for transmitting credentials and email data.