---
title: "Register Microsoft 365 Source Within Cohesity"
slug: "register-microsoft-365-source-within-cohesity"
updated: 2026-04-15T18:11:14Z
published: 2026-04-15T18:11:14Z
canonical: "kb.expedient.com/register-microsoft-365-source-within-cohesity"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://kb.expedient.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Register Microsoft 365 Source Within Cohesity

### Introduction

To protect your Exchange Online data, you need to register your Microsoft 365 domain as a source in Cohesity. After registering your Microsoft 365 domain as a source, you can:

- Update the Microsoft 365 source configuration.
- Refresh the source details.
- Unregister the Microsoft 365 domain from the Cohesity Platform.

### Register Microsoft 365 as a Source

Before you register Microsoft 365 as a source on Cohesity Platform, ensure that you:

1. Review the [Considerations and Best Practices](https://kb.expedient.com/v1/docs/m365-considerations-and-best-practices), [Firewall and Port Requirements](/v1/docs/firewall-and-port-requirements), [User Roles and Application Permissions](/v1/docs/user-roles-and-application-permissions-for-o365), [Microsoft 365 User Account](/v1/docs/microsoft-365-user-account), and [Custom Application Within Azure Portal](/v1/docs/custom-application-within-azure-portal) requirements.
2. Perform the prerequisite tasks detailed in those documents.

To register Microsoft 365 as a source:

1. [Login](https://kb.expedient.com/docs/how-to-access-cloud-data-protection) to the Cohesity Dashboard and select **Data Protection** > **Sources**.
2. Click **Register** on the top-right of the page and then select **Microsoft 365**.
3. In the **Register Microsoft 365 Source**page, perform the following:
  1. Follow the prompts to configure the M365 Applications that Cohesity will discover as needed
  2. The options for **Fetch Mailbox Info, Fetch OneDrive Info, Include Users Without MySite,** and **Enable Site Tagging** is recommended to be disabled
  3. Input the user account that would the owner for the Cohesity Entra App
  4. Follow the document [Cohesity - Remediation-M365 Azure ACS Retirement](/v1/docs/cohesity-remediation-m365-azure-acs-retirement-1) to configure certificate based
  5. We encourage that OAuth is enabled if possible
  6. *Optional.* To enable exporting and downloading mailboxes or email(s) in PST format, toggle on **Use Windows Proxy** and specify the hostname (FQDN) or server IP of the Windows Proxy added as a physical server.
4. Click **Register**.

You can add multiple Azure apps for a Microsoft 365 source to load balance the backup and restore operations. Click **+** to add multiple Azure apps. Also, ensure that you provide the valid **App ID** and **App Secret Key**.

The security defaults are enabled by default on recently created Microsoft 365 domains. For more information, see [Security defaults](https://docs.microsoft.com/en-us/azure/active-directory/fundamentals/concept-fundamentals-security-defaults) in Microsoft documentation. Registering the Microsoft 365 domain as a source fails if security defaults are enabled on the Microsoft 365 domain. Ensure that you toggle on **Enable OAuth** while registering the Microsoft 365 domain as a source.