Marketing Cloud Engagement can authenticate using your token resolver service with HTTP basic authorization or OAuth 2.0. Apex REST isn’t supported.
Basic Authorization
Tokenized Sending supports username and password authentication. Configure your endpoint to listen on port 443. When you implement your API framework, provide login credentials to your account executive. You can also allowlist Marketing Cloud Engagement IP addresses to secure your interactions.
OAuth
Tokenized Sending supports the client_credentials grant specified in the OAuth 2.0 specification. Engagement provides a username, password, and scope access to an OAuth endpoint and provides the resulting bearer token when accessing information from your data system.
To troubleshoot issues related to OAuth, log in as an admin. Then, check the setting at .
Although the MCE token request service connects to an OAuth 2.0 endpoint, using OAuth 2.0 doesn’t increase the security of the token exchange any more than the default HTTP Basic authentication. Using OAuth 2.0 adds increased overhead and network traffic during sends.