The POP3 server address is poppy.mailsac.com
Instructions for reading email via POP3, REST API, and the Mailsac website are available in the documentation
Checking mail via POP3 requires a private address
The essential settings for checking via POP3 are:
Server: poppy.mailsac.com
Email Address/Username: email address being checked
Password: SMTP Key
Port: 110
Auth Settings: Password / allow plain / insecure (specifically, Mailsac supports LOGIN and PLAIN protocols)