Content Search for Targeted Collection of Inactive Mailbox Data

JeremyTBradshaw, thanks for your comments. The -IncludeSoftDeletedRecipients switch is reliable for the time being, I've learned that some organizations are already using it for existing inactive mailboxes to prepare for the method presented in this post, so it's a great option for customers who don't have the data in advance. That said there are code-based differences between soft-deleted and inactive mailbox handling, like with the Get-Mailbox cmdlet. It has switches for inactive but also a separate one for soft-deleted. While the -IncludeSoftDeletedRecipients works in Get-MailboxFolderStatistics for inactive mailboxes presently I can't say with certainty that it will 1, 5, or 10 years from now. Cmdlets change, switches and their behavior are added and dropped, so the "critical prerequisite" statement reflects that concern.

I agree there's overhead involved to satisfy it (which can be minimized with investment in PowerShell or Power Platform automation), but I think it represents a worthwhile insurance policy in a situation where there's no guarantee/supportability statement that the cmdlets will always work the way they do today.* If the overhead to collect the data is a serious concern maybe a part 2 post makes sense about how to automate the process. I'm thinking of a script approach that ingests a CSV of mailbox IDs to run Get-MailboxFolderStatistics against them and use Graph to put the data for each into their respective mailboxes. Maybe someone else is thinking Power Automate, whatever might work!

* It's worth stating that my comments are hypothetical and are not statements about real or planned changes to the cmdlets discussed!