This Exchange Server 2010 article will show you how to set a Mailbox size Limit on a group of users using a PowerShell cmdlet.
Get Started
To do it copy all user names to a text file and save to c:\list.txt and run the following cmdlet from the EMS:
get-content c:\list.txt | Set-Mailbox -UseDatabaseQuotaDefaults $flase -ProhibitSendReceiveQuota 500mb
the cmdlet above will set a mailbox limit of 500MB to all users in the list.
To set the limit the one user type
Set-Mailbox test10 -UseDatabaseQuotaDefaults $flase -ProhibitSendReceiveQuota 500mb
