Question:
How do I get a list of all mailboxes in my Exchange organization, with their SMTP addresses?
Answer:
The most appropriate report template to use would be Selected Attributes From Mailboxes, that you will find on the Templates > Inventory menu.
You would select all mailboxes in the organization, select at least three attributes (First name, Last name, Email address) and export your report as a CSV file, and then open that file in Excel.
You would obtain a report such as this one:
Article ID: 10203, Created: December 13, 2010 at 4:32 PM, Modified: January 23, 2018 at 5:56 PM