Every incoming email is passed through the following sequence of spam and virus filters;

  1. Reverse DNS blacklisting
  2. XBL blacklisting
  3. Malicious attachment blocking
  4. Phishing Email Scanning
  5. Image spam filtering
  6. SPF – Sender Policy Framework
  7. User trainable Bayesian filter

If a virus or malicious attachment is found, the message is deleted at the incoming mail server.

If a message is detected as originating form a blacklisted mail server, it is rejected at the server level and an email is sent to the sender notifying them that their IP address is listed as a blacklisted IP address.

If a message is detected to contain a known blacklisted URL/Link, then the message is rejected and the sender is notified that the content contains a blacklisted URL/Link.

If the SPF checks determine the email is not from the senders domain name or the message is flagged by the Bayesian filter, the message header (X-ME-Content: Deliver-To=Junk) is added to the email message.

We do not delete messages at the server level in this incidence as no spam system can be 100% accurate and we do not wish to risk deleting genuine emails.