Graph error when using Sendmail as impersonated user

Error Message

When you are trying to use the Send Mail action as an Impersonated User, you may receive the following error message:

What's the Issue?

This error likely indicates a permissions issue. When you send mail via this endpoint there are a few factors that come into play:

When using Rewst and sending this call from the MSP tenant, it's going to use application permissions. But if the call is done with CSP, it's going to use delegated authentication, meaning access to an external user/identity mailbox will not be granted.

How to Resolve This Issue

If you receive this error when the call is being made with the MSP tenant, then it is necessary to check the following:

  1. Log in to Entra in the MSP tenant.

  2. Verify that the permission shows in the Permissions page for the Rewst Prod enterprise app.

  3. Click the Grant Admin Consent for button If the permission is missing

  4. Follow the wizard for granting consent.

  5. Verify permission now exists.

  6. Test the workflow, if successful stop here.

If the test is unsuccessful then follow these next steps:

  1. Re-authorize the CSP integration.

  2. Re-authorize the Graph integration without the CSP delegation slider checked.

  3. Re-authorize the Graph integration with the CSP delegation slider checked.

  4. Repeat these re-authorization steps for the Exchange Online integration.

Contact Us for More Help

If you're continuing to have issues, check out our ROC support page to get help!

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