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 Software Downloads > Email Tools Utilities > Open Relay Filter Enterprise Edition
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. When ORF detects that an incoming mail is a spam, it rejects the mail by rejecting either the sender or the recipient(s) of the email. ORF's most effective spam filtering feature is the ability to use multiple external spam source databases (DNS blacklists) simultaneously. ORF is shipped with dozens of DNS blacklist definitions and the list can be extended. Most of these DNS blacklists are updated almost every second which guarantees that ORF can block even the most up-to-date spam attacks. For the most effective filtering ORF also offers custom tests in addition to the DNS blacklists usage. The reverse DNS (RDNS) test can reject emails coming from fake, non-existent domains, the FQDN test is for blocking emails with broken sender information. You can also create your own IP address, subnet mask, 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 reject messages from specific hosts or IP ranges, senders (domains) or local mailboxes. ORF can be used with Windows 2000 built-in IIS SMTP Service and Microsoft Exchange Servers (which use this service for SMTP communication). ORF was designed with high-performance and robustness in mind. We have built in a configurable DNS cache that can store DNS lookup results. This saves you bandwidth and increased throughput because the same DNS lookup does not have to be performed twice. Unlike many other spam content filters, ORF utilizes nearly 0% processor time, because it does not do too many processor and memory-intense string operations. ORF performs well even under heavy usage. It is being used in networks with a daily average of half-a-million incoming mail without any performance problems.
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