Issue
Mailboxes with Microsoft API generate the Error “MailboxNotEnabledForRESTAPI.”
Environment
NinjaOne SaaS Backup
Cause
This error occurs when the mailboxes in question do not have REST API access.
Resolution
To fix the error, the tenant’s administrator must enable REST API Access for those mailboxes.
Additional Resources
For more information on this error, reference Microsoft: REST API is not yet supported for this mailbox error for request to a mailbox (external link)