Policy Reduction

The policy reduction defines which policy, if any, is applied to the email. If an email has more than one recipient, each recipient is treated as a separate email.  The different email addresses could resolve to different policies because the addresses match different matching criteria.

The ZixGateway appliance uses an algorithm to determine which policy to apply to the email, starting with the most general matching criteria to the most precise matching criteria.  The precision of the matching criteria in a policy is determined by the number of criteria to be matched.  If two policies have the same number of matching criteria, then the algorithm looks at the precision of values of the criteria.

A policy that sets the To and From pattern is more precise than a policy that just sets the To pattern.  A policy that searches the Subject, Body, and Attachment is more precise than a policy that just searches the Subject and Body.  A policy that references two Glossary entries is more precise than a policy that references one Glossary entry.  A policy that sets the To value to user@domain is more precise than a policy that sets the To value to *@domain.

ZixGateway uses the following steps to determine which policy is applied to the email.

• If the email matches only one policy, the related actions are taken.
• If the email matches more than one policy and the policies share actions in common, the related policies are combined and the actions they share in common are those that are taken.
• If the policies are on the same hierarchical level and their actions do not share anything in common, then the email is bounced/not sent. The email bounces because the policies conflict. You need to reexamine the policies and remove the conflict.
• If the policies are on different hierarchical levels and their actions do not share anything in common, then the most restrictive policy is carried out.

A policy can contain more than one method of sending an email.

Main Topic

Structuring Policies