Transport rules on Hub Transport servers are important for applying message policies foryour Exchange organization. In general, they are used to apply compliance and policy-basedrules to messages. Many organizations require message policies because they are forced bylaw, regulatory requirements, or company policies to limit the interaction between certaindepartments or people.
For example, certain workers may be allowed to communicate withtheir colleagues, but not with external recipients on the Internet. In general, you can use transportrules to perform the following tasks:
- Filtering confidential information
- Preventing confidential/company-sensitive information from leaving the organization
- Redirecting messages for inspection or preventing receipt of inbound and outbound messages
- Adding disclaimers to messages
- Applying an ethical firewall where people are not allowed to communicate with each other
The transport rules on the Hub Transport servers are managed centrally using the EMC. They are stored in Active Directory and are applied to every Hub Transport server once ActiveDirectory replication takes place. Therefore, you only can apply a transport rule globally to allHub Transport servers. Applying it to a single server is not possible.Now that you know the key differences between transport rules on a Hub Transport serverand on an Edge Transport server, let’s take a look at how these rules are implemented.
Each transport rule consists of the following components:
Conditions. Conditions are used to select the messages that will be subject to the transportrule action. If you do not select any condition, it will be applied to all messages.
Exceptions. Exceptions are used to identify messages to which the transport rule actionshould not be applied. You don’t need to configure exceptions if you don’t require them.
Actions. Actions are what will happen to the mail you specified using conditions and exceptions. You must have at least one action configured for every rule.Additionally, when you create multiple rules, each rule will receive a priority. Using these priorities, you can control which rule will act on a message first. Rules with a lower prioritywill be processed first. For example, say you have two rules that apply for the same recipient;one rule is priority zero and the other rule is priority one. The priority-zero rule will first processthe message, then the priority-one rule will process that same message. You may want tomodify this if there are two rules that contradict or influence each other.