Read the POP3 RFC, RFC 1939. What is the purpose of the UIDL POP3 command?
Read the POP3 RFC, RFC 1939. What is the purpose of the UIDL POP3 command?
UIDL means “unique-ID listing”.
When a POP3 client issues the UIDL command, the server responds with the unique message ID in mailbox.
It is useful for “download and keep”.