Technology

No single method of stopping spam is effective at present and we use a mixture of anti spam technologies at various points in the mail process to minimise the amount of junk hitting your inbox.

Spam Assassin

SpamAssassin is a mature, widely-deployed open source project that serves as a mail filter to identify Spam. SpamAssassin uses a variety of mechanisms including header and text analysis, Bayesian filtering, DNS blocklists, and collaborative filtering databases. New Spam Assassin rules are published daily to catch new spam patterns.

Clam AV Antivirus

Clam AntiVirus is an open source (GPL) anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail gateways. It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. We update our AV signatures 12 times a day.

DKIM (Domain Keys Identified Mail)

DomainKeys is a method of e-mail authentication in which outgoing mail contains an encrypted signature specific to the sending domain and on receipt the key is compared with the Public key. If the two values match, this cryptographically proves that the mail originated at the purported domain and has not been tampered with in transit.

SPF (Sender Policy Framework)

Normal SMTP allows any computer to send an e-mail claiming to be from anyone. Thus, it's easy for spammers to send e-mail from forged addresses. This makes it difficult to trace back to where the spam truly comes from, and easy for spammers to hide their true identity in order to avoid responsibility. Many believe that the ability for anyone to forge sender addresses (also known as Return-Paths) is a security flaw in modern SMTP, caused by an undesirable side-effect of the deprecation of source routes.

SAV Sender Address Verification

SAV is a lightweight, fast and reliable Sendmail milter that implements a real-time Sender e-Mail Address Verification technology. This technology can stop some kinds of SPAM with a spoofed sender's e-Mail address.

Real time Blacklists (RBL/DNSBL)

A DNSBL (commonly known as a 'Blocklist") is a database that is queried in realtime by Internet mail servers for the purpose of obtaining an opinion on the origin of incoming email. The role of a DNSBL such as Spamhaus' SBL/XBL/PBL Advisory system is to provide an opinion, to anyone who asks, on whether a particular IP Address meets Spamhaus' own policy for acceptance of inbound email.