Forum Discussion
Exporting list of Outlook client versions
Go to the O365 admin portal -> Reports -> Usage -> Email app usage -> press the Export button. No way to get this report via PowerShell afaik (Anne Michels might prove me wrong here).
If you need even more details compared to what's shown in the report, down to the individual build number, you will have to browse the Audit logs and get the relevant data from them.
If you want to get Outlook client versions:
Manual method
Check each user’s Outlook via File → Office Account → About Outlook.
Or collect versions directly from users.
Note: This works for small setups but is slow for large organizations.
For larger setups, you can use Exchange Online PowerShell to get mailbox connection data, or tools that back up mailboxes. For example, you can back up mailboxes and review email headers for client info — it’s safer than manually checking every machine.
Bulk / Automated
For larger environments, you can use https://www.recoverytools.com/backup/office365/ by RecoveryTools. While it doesn’t directly report Outlook versions, it can back up mailboxes and let you review email headers and metadata, which sometimes include client info.
More details on safely exporting and managing emails can be found here: Email Backup Wizard Blog
https://emailbackupwizard.com/blog/extract-email-addresses-from-outlook-365/?