Office 365 Exchange scanner e-mail outside organization without account

Software & Operating Systems
1

I’m attempting to set up a scanner to send e-mail via an Office 365 subscription (Enterprise E3) to scan to e-mail addresses outside the organization. It can scan to the organizations e-mail addresses without a subscription and authentication but fails to scan to other addresses. Is the only way to make this work to buy a subscription for the scanner if I want to use the SMTP servers offered by Microsoft?

Currently the scanner uses the SMTP server company-name.mail.protection.outlook.com without authentication.

2

One can add external addresses as contacts in the exchange admin center and that passes mail to the external address.