- MailHurdle anti-spam technology
- inbound and/or outbound filtering
- flexible content-filtering
Mirapoint is a long-established vendor of both secure mail servers and, more recently, the RazorGate family of security appliances. The RazorGate 100 is smallest of that range, but runs the same Unix-derived OS together with Sophos antivirus and a SpamAssassin derived anti-spam filter (due to be replaced by a CommTouch product by the end of 2004). The Mirapoint RazorGate 100 costs £4,500 for up to 100 users.
A 1U rack-mount appliance, the RazorGate 100 features an Intel Xeon processor and attaches to the local network via a 10/100Mbps Ethernet interface with a separate port for management if required. The appliance acts as mail router and can be configured to process incoming or outgoing messages specifically, or both. As with many other mail server appliances, it will work with any SMTP mail server and can handle multiple domains.
The browser-based management interface is neat and very logical, if not the most intuitive ever invented. Still, it’s easy enough to master, and using the default settings the RazorGate 100 can start filtering mail in around about an hour. The anti-spam and virus tools are enabled by default and can be fine tuned in various ways, including custom black/white lists and links to external blacklist services. A spam threshold can also be set, and a unique option called MailHurdle enabled.
MailHurdle looks for received messages with a mix of unknown IP address, email to and email from addresses. Such messages are initially rejected causing real mail servers to re-send, but most spamming software won’t bother. Where a resend isn’t received before the pre-set timeout expires, the address combination is marked down as a source of spam -- an approach which by itself can reduce spam traffic by 50 to 80 per cent.
RazorGate filtering is a two-stage process with messages first marked up and then processed. Preset filters are included, but custom filters can also be configured. Customisation facilities are extensive: for example, you can monitor or block messages to/from specific addresses and filter on key words in the subject or body of a message. The two-stage filtering process also allows marked-up messages to be processed by the target mail server rather than the appliance itself. For example, you can deliver suspected bulk mail to specific folders within in a user mailbox rather than block or quarantine it centrally.
The current RazorGate family doesn't allow users to manage quarantined messages or white/black lists themselves, although there is an add-on to do this which will be incorporated into the next OS release (due by the end of 2004). There’s also a separate quarantine manager account to manage quarantined messages via a built-in Web mail interface.