What is the POP3 Server Address?

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)