You can control certain aspects of VPOP3 by sending emails to 'mailer_daemon@<your domain>'
The subject line must be one of the lines below:
(Not supported in VPOP3 version 5 or later)
Send a message containing
USERNAME <username>
PASSWORD <password>
(If you use SMTP authentication to send the message, then this is not required)
then one or more of the following commands: