Exchange Shared Mailboxes: Pulling Full Mailbox Information

Getting a full inventory of every shared mailbox in your organisation — including size — is a single Exchange Management Shell (EMS) command, useful for periodic audits or capacity planning.

On-Screen View

Get-Mailbox -RecipientTypeDetails SharedMailbox -ResultSize Unlimited | Format-Table Name, Identity, ItemsInFolder, FolderSize

Export to CSV

For anything beyond a quick glance, exporting to CSV (then opening in Excel for formatting) is far more usable:

Get-Mailbox -RecipientTypeDetails SharedMailbox -ResultSize Unlimited | Select-Object Name, Identity, ItemsInFolder, FolderSize | Export-Csv C:\SharedMailboxInfo.csv -NoTypeInformation

Replace C:\SharedMailboxInfo.csv with whatever export location and filename suits you. Note the swap from Format-Table to Select-Object in the export version — piping Format-Table output into Export-Csv produces a broken, unusable CSV, since Format-Table is meant for screen display, not structured data output.

Exchange Online Equivalent

If your mailboxes are in Exchange Online (or a hybrid environment where you’re querying the cloud side), use the modern Get-EXOMailbox cmdlet from the ExchangeOnlineManagement module instead of Get-Mailbox — it’s built specifically for Exchange Online, and Microsoft recommends it over the legacy remote-PowerShell cmdlets for better performance and reliability at scale:

Connect-ExchangeOnline
Get-EXOMailbox -RecipientTypeDetails SharedMailbox -ResultSize Unlimited | Select-Object Name, Identity, ItemsInFolder | Export-Csv C:\SharedMailboxInfo.csv -NoTypeInformation

One thing to watch: Get-EXOMailbox doesn’t return FolderSize directly in the same way — for mailbox size specifically, pair it with Get-EXOMailboxStatistics (which returns TotalItemSize) and join the two on the mailbox identity if you need size and general shared-mailbox metadata in one export.

Adding More Detail

Both commands above can be extended with extra properties useful for an audit — for example, adding Department, Office, or GrantSendOnBehalfTo (to see who’s been given send-on-behalf rights to each shared mailbox) to the Select-Object list turns this from a simple inventory into a genuinely useful access-review report.

Resources

• our PowerShell script collection