I tried that last night. I set up a client address set with the specific IPs we want to receive mail from and changed the SMTP server rule for routing mail to Exchange so that it applies to only the new client address set. I restarted the server after making that change and confirmed that the change is still there, but we're still getting mail from other IPs. I wonder if ISA also requires a positive "reject" rule regarding mail from other IPs? Thanks. Dana