Web Wiz DNSBL Spam Database Lookup
To ensure that our customers receive high quality email services free from Spam, Web Wiz uses DNS-based Block Lists (DNSBL) to block email that is sent from known spam sources.
In order to prevent false positives we use multiple Block Lists from Web Wiz (DNSBL), SpamHaus, Abusix Mail Intelligence, Barracuda (BRBL), HostKarma, Spam Eating Monkey and SpamCop. The source IP address must be listed in multiple block lists before we block email sent from an IP address.
The weighting given to each block list is reviewed regularly against our own live mail traffic, rather than being left at supplied defaults, so that lists which perform well on our network count for more and those which do not count for less.
Web Wiz maintain our own Web Wiz DNSBL Database of IP addresses. Most IP addresses are listed as a result of directly sending spam our customers. This list is manually maintained to ensure that the quality is high.
Content Filtering and Message Scoring
Block Lists deal with where a message came from. Every message that passes them is then scanned for its content and given a spam score, using Rspamd running on our own infrastructure in our UK data centre.
Rspamd combines a wide range of checks into a single score, including statistical analysis of the message content, fuzzy hashing to recognise bulk campaigns already seen elsewhere on our network, URL and domain reputation, and the structural tricks commonly used to disguise spam. Messages are then delivered, marked or moved to the Junk Email folder according to that score.
Because we host the engine ourselves rather than relying on an external service, it learns continuously from the mail actually arriving on our own platform, and we are able to tune it directly in response to what our customers are seeing.
How Our Filters Learn
When a user marks a message as junk, or moves one out of their Junk Email folder, that decision can be used to train our filters. Before it is, the correction is reviewed to check that it is sound, because a message moved to the Junk Email folder is not always spam. Many are newsletters the recipient no longer wants, or mail they are simply deleting.
That review uses an AI service provided by Anthropic. The message headers, subject and a short extract of the message are sent for that purpose only. This applies solely to messages a user has already sorted themselves, it plays no part in deciding what happens to any message, and it never affects delivery or filtering.
Email Authentication
Alongside content scoring, every inbound message is checked against the sender's published authentication records using SPF, DKIM and DMARC. These confirm that a message genuinely came from the domain it claims to be from, which is the most reliable defence against phishing and brand impersonation.
If you are having trouble sending email to Web Wiz customers, checking your own SPF, DKIM and DMARC records is the best place to start. Our free Network and Website Tools can check these for any domain.
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