EWS – Using EWS to Access O365 Mailbox

exchange-2013microsoft-office-365

We're trying to allow vendors to use EWS to connect to mailboxes on O365. We've disabled MFA for this specific user.

When we test connection to the EWS test site https://outlook.office365.com/ews/exchange.asmx internally in the corp network, it works. We get a prompt to enter userUPN and password.
When we're trying outside of the corporate network, we get a prompt for userUPN and password. However, we can get through. It times out.

Does anyone know if this is the correct EWS link to test if it's working? Does that authentication come back to the corporate ADFS?

Best Answer

Do you deploy hybrid? Or just sync via AAD connect? Do you deploy ADFS?

  1. Browse to https://testconnectivity.microsoft.com. This is a Microsoft-owned tool.
  2. If using Office 365, click on the Office 365 tab.
  3. Select Service Account Access (Developers) and click on Next.
  4. Specify the target mailbox email address.
  5. Specify the service account user name (if using admin credentials on the connector, enter the exact same user name).
  6. Specify the service account password (if using admin credentials on the connector, enter the exact same password).
  7. Check Specify Exchange Web Services URL and specify the URL (example: https://server/EWS/Exchange.asmx).
  8. If using Exchange Server, do not check Use Exchange Impersonation. If you are using Office 365, and using impersonation, do check the box.
  9. Check Ignore Trust for SSL.
  10. Click on Perform Test.
  11. Once results are displayed, check the overall result, and also click on Expand All.
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