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To integrate with Microsoft, you have to create an application in the admin center. You can find more details about creating an application here https://learn.microsoft.com/en-us/graph/auth-register-app-v2 .
Prerequisites
A Microsoft Entra ID tenant.
An account that has at least the Cloud Application Administrator role.
Register an application
Go to the Microsoft Entra admin center https://entra.microsoft.com/.
If you have access to multiple tenants, use the Settings icon in the top menu to switch to the tenant in which you want to register the application from the “Directories + subscriptions” menu.
Browse to Identity > Applications > App registrations and select “New registration”.
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That's all the Office 365 integration, now, you can connect your Office 365 to the Inbox > Channels > Email in your tenant here https://cloudfon.atlassian.net/wiki/spaces/CX/pages/49283141/3.1.1+Email#Office-365-account or your SMTP server here 9.2.2 Custom SMTP Server ！