RFC-1939 ● Post Office Protocol - Version 3

PASS string

Arguments:

a server/mailbox-specific password (required)

Restrictions:

may only be given in the AUTHORIZATION state immediately after a successful USER command

Discussion:

When the client issues the PASS command, the POP3 server uses the argument pair from the USER and PASS commands to determine if the client should be given access to the appropriate maildrop.

Since the PASS command has exactly one argument, a POP3 server may treat spaces in the argument as part of the password, instead of as argument separators.

Possible Responses:

+OK maildrop locked and ready

-ERR invalid password

-ERR unable to lock maildrop

Examples:

C: USER mrose

S: +OK mrose is a real hoopy frood

C: PASS secret

S: -ERR maildrop already locked

...

C: USER mrose

S: +OK mrose is a real hoopy frood

C: PASS secret

S: +OK mrose's maildrop has 2 messages (320 octets)