Problem statement
This article will explain a potential cause when the following error is received while following the steps in Configure Microsoft 365 Exchange Online as External SMTP Email Provider at the Send a test email step.
Error sending email: Access is denied. Check credentials and try again.
Symptoms
We followed the steps in this doc:
but sending test email produced the following error:
Error sending email: Access is denied. Check credentials and try again
Solution
Ensure that the Microsoft Graph Mail.send permission is set as an Application permission and not a Delegated permission.
- In the document: Configure Microsoft 365 Exchange Online as External SMTP Email Provider, in Step 5, Add the Mail.Send permission by selecting Add a permission > Microsoft Graph > Application permissions selector:
- After selecting Microsoft Graph ensure that Application permissions is selected before selecting Mail.send.
- Ensure a 365 Admin grants admin consent to the application.