Verify you have the profile: Microsoft Exchange Online
- Go to Settings> Email Configuration> Email Server Profiles.
- Select Active Email Server Profiles and then check if the Microsoft Exchange Online profile is in the list. If the Microsoft Exchange Online profile is missing then verify if you have an Exchange Online subscription and whether it exists in the same tenant as your Customer Engagement apps subscription or not.
- If there are multiple profiles then select the Microsoft Exchange Online profile and set it as default.