View Mailbox Sizes for Exchange 2003 and Exchange 2010 through Powershell

If you need to view mailbox sizes for users in your Exchange organisation, you can do this from an Exchange Management Shell (EMS) for both Exchange 2003 and Exchange 2007/2010.

For your Exchange 2007/2010 users use the following command from EMS:

get-mailboxstatistics | fl displayname,totalitemsize

For your Exchange 2003 users use the following command from EMS:

Get-Wmiobject -namespace root\MicrosoftExchangeV2 -class exchange_mailbox -computer Ex2003ServerName | sort -desc size | select storageGroupName,StoreName,MailboxDisplayName,Size,TotalItems