Configure OWA 2003 Attachment Blocking

How do I configure attachment blocking in Outlook Web Access on Exchange Server 2003

There are 2 levels of file attachments for Outlook Web Access. Level1 attachments have file extensions that are prohibited from accessing by OWA. Level2 attachments have file extensions that can be accessed, but only if saved to the client's file system first.

OWA is installed with a default set of file extensions for the two levels as shown in the following registry keys:

Level 1 attachments
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeWeb\OWA
Value: Level1FileTypes
Type: REG_SZ
Value Data:

ade,adp,app,asx,bas,bat,chm,cmd,com,cpl,crt,csh,exe,fxp,hlp,hta,inf,ins,isp,js,jse,ksh,lnk,mda,mdb,mde,mdt,mdw,mdz,msc,msi,msp,mst,ops,pcd,pif,prf,prg,reg,scf,scr,sct,shb,shs,url,vb,vbe,vbs,wsc,wsf,wsh

Level 2 attachments HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeWeb\OWA
Value: Level2FileTypes
Type: REG_SZ
Value Data:

ade,adp,asx,bas,bat,chm,cmd,com,cpl,crt,exe,hlp,hta,htm,html,htc,inf,ins,isp,js,jse,lnk,mda,mdb,mde,mdz,mht,mhtml,msc,msi,msp,mst,pcd,pif,prf,reg,scf,scr,sct,shb,shs,shtm,shtml,stm,url,vb,vbe,vbs,wsc,wsf,wsh,xml,dir,dcr,plg,spl,swf

Attachments listed should be separated by a comma with no space.