How do I check if a mailbox is accessible using EWS

You can verify independently whether a mailbox is accessible using EWS by performing the following steps:

1. Browse to https://www.testexchangeconnectivity.com (this is a Microsoft owned tool)
2. Select Service Account Access (Developers) and click "Next"
3. Specify the target mailbox email address
4. Specify the service account user name (if using admin credentials on your connector, enter the exact same user name)
5. Specify the service account password (if using admin credentials on your connector, enter the exact same password)
6. Check "Specify Exchange Web Services URL" and specify the URL (ex: https://server/EWS/Exchange.asmx)
7. Do NOT check "Use Exchange Impersonation"
8. Check "Ignore Trust for SSL"
9. Click "Perform Test"
10. Once results are displayed, check the overall result and also click on "Expand All"