Add a Microsoft 365 message source



Microsoft 365 Global Admin Required

You must be a Global Admin in Microsoft 365 to authorize access for all users on your domain.

You can add a Microsoft 365 message source when setting up your Sublime organization or by going to Admin > Message Sources > New message source in the Sublime dashboard and selecting Microsoft 365.

Once you select the option to add a Microsoft 365 message source, the next steps will depend on whether you're using Sublime Cloud or self-hosting Sublime.

Sublime Cloud (Fully Managed)

If you're using Sublime Cloud, simply follow the prompts to authorize access on behalf of your organization.


In order for your self-hosted instance of Sublime to access mail from your tenant programmatically, you must create a new Azure app and authorize it for access. This is required so that only you have access to your mail, and not anyone else, including the Sublime team.

After completing the steps below, you'll copy over the following to add the message source in Sublime:

  • Application (client) ID
  • Directory (tenant) ID
  • Client secret


  1. Login to
  2. Search for App registrations
  1. Click + New registration
  1. Enter "Sublime Platform" for the app name. Leave the other defaults (Single-tenant, no Redirect URI). Click "Register".
  1. Copy the application (client) ID and the Directory (tenant) ID over to the Sublime Platform setup
  1. Click View API permissions and then + Add a permission
  • Select Microsoft Graph
  • Select Application permissions
  • Choose Mail.ReadWrite, User.Read.All, Group.Read.All, and Domain.Read.All
  • Click Add permissions
  1. Then, Grant admin consent for your domain. Note that if this button is greyed out for you, you may need to have a Domain Admin grant the consent.

You should see green checkmarks like this:

  1. Navigate to Certificates & secrets in the sidebar
  1. Create a new Client secret. Enter "Sublime Platform" for the description and choose "24 months".
  1. Copy the client secret "Value" over to the Sublime Platform setup.

:tada: That's it!