POP3 e-mail client class implements the access to mail boxes using the POP3 protocol.

Features of POP3 e-mail client class:
- Support secure connections using TLS
- Provides a stream wrapper class to access messages like files using fopen('pop3://user:pass@localhost/1', 'r');
- POP3 server access using normal and apop login methods
- Authentication mechanisms implemented by SASL client class like: PLAIN, LOGIN, CRAM-MD5, NTLM (Windows or Linux/Unix via Samba), etc..
- Determining mailbox statistics (mail box size in bytes and the number of stored messages)
- Listing of individual message sizes and identifier numbers
- Retrieving messages in data blocks of limited size to not exceed the available memory
- Retrieving messages all at once separating the headers from the body and limiting the number of message lines that may be retrieved at once
- Marking messages to be deleted
- Resetting the list of messages to be deleted
- Issuing of protocol NOOP command to avoid connection shutdown while in idle state