ndMail is NetDocuments Integration with Office 365. It can stop working when the office 365 account password changes. Here is how you can check
Step 1: Co to Hi, First Name –> Admin
Step 2: Click ndMail Configuration
Step 3: Click on the Connection under Host
Step 4: Click Test connection
If it says the connection is valid, you are fine. It it doesnt say that, you need to re-enter the the new ndmail@yourdomain.com password.
Step 5: Click Edit
Step 6a: If using Basic Authentication enter the Password here
Step 6b: If you using Modern Authentication, click on Reauthorize and login to office 365