Login credentials sent via the USER/PASS commands.
Remote POP3 host.
OptionalportRemote port; defaults to 995 (implicit TLS).
OptionaltimeoutPer-operation read deadline in milliseconds.
OptionaltlsTransport security:
'implicit' (default): TLS from the first byte (POP3S, port 995).'starttls': plaintext, upgraded with the STLS command (port 110).'off': plaintext with no upgrade (trusted internal / dev servers).
Options for connect and retrieveAll.