Sending Mail through Graph API if local disk is full by leveraging Azure Arc Managed Identity and Keyvault

This is a request coming from Discord: how to send an email through Graph API if the local disk is full?

Preparing requirements

  1. Create the application and apply the Mail.Send Graph API permissions:
  2. Prepare the Hybrid Join and Key Vault:


Here is the architecture we’re looking at:

The flow is going to be:

  1. The script connects to Azure Powershell using the Managed Identity available through Azure Arc
  2. The script uses Get-AzKeyVaultSecret to pull the Application secret from the key vault
  3. The script sends an API call to request a bearer token to impersonate the Application
  4. The script checks if any of the local disks are full
  5. The script uses the previously-obtained bearer token to send mail through Graph API if a disk is full


First things first, pull the repository locally: Raindrops-dev/RAIN-BlogPostsCode: Companion repo to blog posts (

In my case it’s been done to C:\Temp through Github Desktop:

Open the folder in VsCode and duplicate EmailConfig.json.example to EmailConfig.json:

Fill in the empty brackets with the correct values from the previously created resources:

  • AppID: Application ID of the Mail Sender Application
  • KeyVaultSecretName: The name of the Secret in Key Vault that contains the Application Secret
  • KeyVaultName: The name of the Key Vault
  • EmailSender: The email address from which the email will be sent
  • EmailReceiver: The email address to which the email will be sent
  • TenantID: The ID of your Azure AD tenant

Save the file and exit

Open a Powershell window as admin and go to where the repository has been cloned and run Send-MessageIfDiskFull.ps1:

Et voilà! The script sends the email with the disk whose free disk capacity is less than 10%!

This concludes the 3 part series concerning email sending through Graph API if disk is full.


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