Postfix cannot receive emails using outlook

Postfix cannot use outlook to receive emails-Linux Enterprise Application-Linux server application information. For details, refer to the following. Environment:
Domain Name: The domain name has been registered with the public network, and no DNS server has been set up locally.
Server Platform: postfix + dovecot
If you use telnet localhost 25 to log on, you can send and receive emails normally. If you use outlook to send and receive emails, you can also use telnet localhost 25 to view emails sent using outlook, however, when outlook is used to receive emails, the password is rejected ".
What is the problem .. I checked a lot of information on the Internet and said it was encrypted. If this is the problem, where is the encryption. The file to be changed.