Is it possible to have the above search the AD for a recipient and drop the incoming message if the search is null? We use GFI MailEssentials and it performs this task very well using LDAP. However, I want to drop these messages on the edge - before they hit the internal GFI apps. If not IIS SMTP VS, would you know of any other product that sits on the edge weeding out directory harvesting attempts? Greg System: ISA Server 2006 IIS6 with SMTP virtual server IIS6 with SMTP vs GFI MailEssentials/MailSecurity Exchange 2003 - Clustered All mail to and from this domain is scrutinized by GFI.