SENT: +OK POP3
RECEIVED: USER example@example.com
SENT: +OK Send y our password
RECEIVED: PASS ***
SENT: +OK Mailbox locked and ready
RECEIVED: CAPA
SENT: -ERR Invalid command in current state.
RECEIVED: LIST
SENT: +OK 8598 messages (137625842 octets)
SENT: 1 7527[nl]2 1808...
RECEIVED: UIDL
SENT: +OK 8598 messages (1376255842 octets)
RECEIVED: RETR 1
SENT: .
RECEIVED: RETR 2