ORF Enterprise Edition is an enterprise-level anti-spam solution that helps you to block spam before it reaches your network. It wedges into the SMTP conversations and monitors all incoming SMTP traffic. For the most effective filtering, ORF uses a combination of anti-spam technologies, such as DNSBL's, SURBL's or Greylisting to identify and blacklist unsolicitied emails. Custom tests are provided in addition to the above, e.g. regular expression-supported keyword filtering, attachment filtering or Active Directory-based recipient validation. Using the self-learning Automatic Sender Whitelist of ORF, you can eliminate false positives effectively. You can also create your own IP address, sender and recipient email address lists. While the whitelists can be used to exclude hosts, senders or local mailboxes from filtering, the same type of blacklists help you to reject messages from specific hosts or IP ranges, senders (domains) or local mailboxes. ORF can be used with Windows 2000/2003 built-in IIS SMTP Service and Microsoft Exchange 2000/2003 Servers (which use this service for SMTP communication). ORF was designed with high-performance and robustness in mind, it performs well even under heavy usage. It is being used in networks with a daily average of 2-3 millions incoming email without any performance problems.