For one of the users the mailbox has reached 4.6GB (hasn't done any archiving) how can I reduce the size of the mailbox on the server?

You did not state what version of Exchange but setting mailbox limit would be one solution that would force him/her to clean mailbox. You can also perform automated mailbox cleanup through Mailbox Manager Policy in Ex2003 or Messaging Records Management Policy (MRM) in Exchange 2007.MVP Exchange Server

Hi,reduce the retension policy dates and force the online maintananaceto force the online maintanance follow the belowAdded below registry key to force maintenance.HKEY_LOCAL_MACHINES\System\CurrentControlSet\Services\MsExchangeIS\ParametersSystemValue Name: Aging Clean IntervalData Type: DWORDRadix: DecimalValue: 1Value Name: Deletion Thread PeriodData Type: DWORDRadix: DecimalValue: 1Value Name: Secure Folder Aging Task FrequencyData Type: DWORDRadix: DecimalValue: 1=> Checked the event logs & it started the online maintenance.=> Event Id 700, 701, 1221 started generating for public folders.

Hello,You can force the online maintenance, but you need make the following changes in the mailbox store before forcing online maintenance.Go to ESM <org name> -> Administrative Groups -> <AG name> -> Servers -> <server name> ->First storage Group -> <mailbox store>Note: Mailbox store is the store where the 4.6 GB mailbox resides.Right click on mailbox store and go to limits tab. change the deletion setting dayas to 0 and 0.Force online maintenance.If you still not able to reduce the size you can perform offlin defragmentation.Check the link below for performing offline defragment.http://support.microsoft.com/kb/328804http://support.microsoft.com/kb/192185 Thanks,Vinod

Hi,Please first create the Personal Folder (.pst) in Outlook, move the email to the .PST using Outlook.Then run online maintenance.The best practice is use MRM feature as John said.ThanksAllen