Cookbook: POP3

Serve POP3 against a Maildir++ root:

cargo run -p pop3 -- 127.0.0.1:1110 localhost ./mail

Default demo credentials: alice / secret. Deliver mail first with smtp-local into the same maildir root, then retrieve with any POP3 client:

# after smtp-local has APPENDed to ./mail/alice/
printf 'USER alice\r\nPASS secret\r\nSTAT\r\nQUIT\r\n' | nc 127.0.0.1 1110

See POP3 for the handler SPI and CAPA surface.