Exploring Transport Rules in Exchange Server 2013

Transport rules have been a feature of Exchange Server since the 2007 version and have been included in Exchange Server 2013 with a number of improvements.

New Features in Exchange 2013 Transport Rules

Microsoft has published a list of changes and improvements to transport rules on this TechNet page.

Support for data loss prevention policies is one of the major new features in Exchange Server 2013, and this integrates with transport rules.

Exchange 2013 also has a number of new predicates (conditions) and actions for transport rules. A few of the highlights are:

Ability to take action on messages that have been sent from specific IP address ranges
Ability to take action on messages that have attachments with specific extensions, or that contain executable content
Ability to stop subsequent rules from processing a message (this will make the order of rules important for some environments)
Ability to generate incident reports to an email address at varying severity levels
Transport rule information is now included in message tracking logs
Rule monitoring to detect and alert on rules that are delaying email delivery

Managing Transport Rules

Transport rules in Exchange Server 2013 can be managed in two ways. The first is by using the Exchange Management Shell cmdlets:

 
 
 
 
 
 
 
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[PS] C:\>get–command –Noun *TransportRule*
 
CommandType     Name
—————–     ——
Function        Disable–TransportRule
Function        Enable–TransportRule
Function        Export–TransportRuleCollection
Function        Get–TransportRule
Function        Get–TransportRuleAction
Function        Get–TransportRulePredicate
Function        Import–TransportRuleCollection
Function        New–TransportRule
Function        Remove–TransportRule
Function        Set–TransportRule

The second is by using the Exchange Administration Center, in the Mail Flow section under Rules.

Managing Transport Rules in the Exchange Admin Center

Creating New Transport Rules

The New Rule wizard behaves in an interesting way in Exchange Server 2013. If you simply click the + button the New Rule wizard begins and exposes a limited subset of the available conditions and actions in the drop down lists.

Creating a new transport rule in Exchange Server 2013

However, there is also a More options link in the wizard start screen.

Exposing more options for transport rules

Clicking that link expands the options available in the wizard to a much more granular set, as well as the ability to set multiple conditions and actions.

Fine-grain controls for transport rules in Exchange Server 2013

Creating New Transport Rules Based on Templates

In addition to the New Rule wizard behavior shown above you can also create a new rule based on a template of sorts. By clicking the little arrow next to the + icon a menu of common rule types is presented to get you started.

Transport rule templates

For example, choosing the “Apply signature or disclaimers” option from the list the new rule starts with the “Append a disclaimer to the message” action already selected.

Transport rule to append a disclaimer to a message

Other templates present different subsets of actions depending on the general purpose that the rule is for. However in all cases it appears you can still click More options to get access to all of the conditions and actions if needed.

Time-Based Transport Rules

Another useful capability of Exchange 2013 transport rules is the ability to set specific dates for the rule to be activated and deactivated.

This could be useful for businesses that need to align their disclaimers with specific events such as a marketing campaign, a holiday period, or corporate merger/acquisition.

Transport Rules Audit Mode

Exchange 2013 transport rules also have an audit mode so that they can be tested without impacting message delivery. In the New Rule wizard these options are visible as the two “Test rule…” modes.

Exchange 2013 transport rule test/audit modes

Although they are referred to as “Test” in the Exchange Admin Center the modes are referred to as “Audit” in the New-TransportRule cmdlet parameters.

So in effect a rule can be placed in one of three modes:

Enforce – the rule is active and all the actions you have specified will be taken
Audit (Test rule with notifications disabled) – the rule is active, and the actions are logged to the message tracking logs, but not actually enforced on the message
Audit and Notify (Test rule with notifications enabled) – same as Audit mode except any “Notify…” actions on the rule are taken

Summary

As you can see a number of improvements have been made to transport rules in Exchange Server 2013 that add more power and flexibility to this feature, which will no doubt help many organizations who rely on transport rules today or who have specific needs that aren’t quite met by the transport rules functionality in previous versions of Exchange.