I know,the problem is many many junk emails using my SMTP Server if I don't auth users(select 'all allow except below' in Exchange System-Default SMTP Vitual Server-Properties-Access-Relay). I ever installed screener according to Microsoft's paper 'Microsoft ISA Server 2000-Configuring and Securing Microsoft Exchange 2000 Server and Clients',in this white paper it seems using SMTP filter and relay restrictions together,but in fact the trouble occured as you know. My aim is how I can use SMTP Filter and prevent junk emails from my mail server simultaneity. Instruct me please.