NM: Powershell Error: Exception calling "Bind" with "2" argument(s) The SMTP address is not assig (B304251)

Issue

A PowerShell error is returned when attempting to run PowerShell commands in Notes Migrator for processes such as the Delegation Migration.
PowerShell error returned: Exception calling "Bind" with "2" argument(s): "The SMTP address is not assigned to a mailbox."

Solution

Verify the Notes Migrator Settings document (Required Settings - Additional tab) for the CAS Server setting and the PowerShell end point setting.
Ensure that these are the correct expected URL's for the migration environment's Exchange or Office 365 host names.
Ensure that the Username is in a UPN format (eg administrator@upndomain.com).
Ensure that the account used is a member of the Application Impersonation Role in Exchange or Office 365.