: auth_only( address, port = 110, account, password )
    POP å򳫤ǧڤԤä³ڤޤ
    POP before SMTP ѤǤ

        # example
        Net::POP3.auth_only( 'your.pop3.server',
                             nil,     # using default (110)
                             'YourAccount',
                             'YourPassword' )

