With Microsoft Exchange Server, there is no easy way via the GUI to view the mailboxes which are taking up the space on the disk drive.
Luckily with Microsoft Exchange Powershell, a simple script which can be run in order to rank the users in mailbox size.
The script below returns the top 10 users, sorted by mailbox size, complete with columns showing the size and number of objects within that mailbox.
Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Sort-Object TotalItemSize -Descending | Select-Object DisplayName,TotalItemSize,ItemCount -First 10
I suppose at some point I could integrate this into Taskcentre so that it emails the users periodically. (I’ve done similar tasks which alerts users when their accounts are locked out of the domain).