A ruleset is a collection of tests that can be performed on an incoming email.

There are two basic classes of rulesets available. Public Rulesets and Private Rulesets. The Public Rulesets are ones which we maintain as a service to our users and which offer a range of general blocking characteristics, details of which can be found here. Private Rulesets are those which individual users maintain themselves to provide a customised filter tuned their particular needs. Both sorts of ruleset have the same capability.

The individual tests are grouped into areas which are used at different points during the reception of a message. The various groups, and their approximate order of evaluation are as follows

  1. Sender Validation Tests
  2. Known IP Addresses, Sender Domains, Sender Email Addresses
  3. Domain Name System Block Lists
  4. Anti Virus
  5. Message Header Tests
  6. Message Content Tests

Rulesets have owners, and in some cases a ruleset can be published for use by other users. Domain administrators may decide to force the use of a given ruleset for all users in that domain to enforce company policy.

All email that is not rejected has a number of header lines added to indicate what if any rule the mail matched. Details of these header lines can be found here.