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You must have at least Application Developer permissions to register the app, and a Global Administrator or Privileged Role Administrator must grant admin consent. Client credentials cannot call /me endpoints, so pass the mailbox owner’s ID or userPrincipalName in the userId input of every action. Webhook events are not supported with this authentication type.

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Register Your Application in Microsoft Entra ID

To use client credentials with Microsoft Outlook, register an application in Microsoft Entra ID and grant it Microsoft Graph application permissions.

1

Sign in to Microsoft Entra Admin Center

Sign in to the Microsoft Entra admin center as at least an Application Developer. If you have access to multiple tenants, click the Settings (gear) icon in the top-right corner, then select the desired tenant from the list under Directory + subscription.

2

Create a New App Registration

Navigate to App registrations by searching from the top search bar and click on New registration.

  • Enter a meaningful Name for your app (e.g., StackOne Microsoft Outlook App-Only).
  • Under Supported account types, select Single tenant.
  • Leave the Redirect URI blank; client credentials does not use a redirect.
  • Click Register to create the app registration.
3

Copy the Application (Client) ID and Directory (Tenant) ID

On the application’s Overview page, copy the Application (client) ID and the Directory (tenant) ID values and store them securely for use later.

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Configure Application Permissions

Grant your application Microsoft Graph application permissions. These apply without a signed-in user and always need admin consent.

1

Open API Permissions

From the left menu under Manage, select API permissions.

2

Add Microsoft Graph Application Permissions

Enables actions: Add Attachment, Copy Mail Folder, Copy Message, Create Child Folder, Create Draft Message, Create Draft Reply All To Message, Create Draft Reply To Message, Create Draft To Forward Message, Create Mail Folder, Create Message In Mail Folder, Create Message Rule, Delete Attachment, Delete Mail Folder, Delete Message, Delete Message Rule, Forward Message, Get Attachment, Get Mail Folder, Get Mail Folder Delta, Get Message, Get Message Delta From Folder, Get Message Rule, List Attachments, List Child Folders, List Folder Messages, List Mail Folders, List Message Rules, List Messages, Move Mail Folder, Move Message, Permanently Delete Mail Folder, Permanently Delete Message, Reply All To Message, Reply To Message, Send Draft Message, Send Mail, Update Mail Folder, Update Message, Update Message Rule

Click Add a permission, select Microsoft Graph, then select Application permissions. Delegated permissions with the same names are ignored by client credentials, so each permission must show Application in the Type column.

  • Search for Mail and MailboxSettings, click expand all, and select the permissions your integration needs.
  • For full mail access: Mail.ReadWrite (Read and write mail in all mailboxes)
  • For sending mail: Mail.Send (Send mail as any user)
  • For message rules and mailbox settings: MailboxSettings.ReadWrite (Read and write all user mailbox settings)
  • Click Add permissions to save.
3

Grant Admin Consent

Click Grant admin consent for [Your Organization] and select Yes. Verify that Granted for [Your Organization] appears under the Status column for each permission. If you add or change permissions after connecting the account in StackOne, reconnect the account so it requests a new access token that includes them.

4

Limit Mailbox Access (Optional)

By default the app can access every mailbox in the tenant. To restrict it to specific mailboxes, an Exchange administrator can use Role Based Access Control for Applications in Exchange Online. Changes can take 30 minutes to 2 hours to apply.

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Generate Client Secret

Create a client secret that StackOne uses to request access tokens.

1

Navigate to Certificates & Secrets

From the left menu under Manage, select Certificates & secrets.

2

Create a New Client Secret

Under the Client secrets tab, click New client secret, add a Description, select an expiration period and click Add.

3

Copy the Client Secret Value

Immediately copy the Value of the newly created client secret and store it securely. This value will only be shown once and cannot be retrieved again.

1

Connect

  • Click Connect.
  • If applicable, the provider will redirect you to a sign-in or authorization page. Complete the provider’s authorization flow.
  • Once authorization is successful, you will see a confirmation popup.
2

Use Actions

Connect an AI platform to the linked account’s actions. See AI Platforms.Other ways to call actions are listed in Protocols & SDKs.

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Next Steps

Webhooks setup

Configure receiving Events for Microsoft Outlook into StackOne.