Executive Summary:
Custom attributes let you go beyond Exchange Server 2007’s precanned filters for dynamic distribution groups.

If you want to go beyond Exchange Server 2007’s precanned filters for dynamic distribution groups, you can configure custom attributes. You must configure custom conditions not only on the dynamic distribution group side, but also on the recipient side—by ensuring that recipients that fall into the scope of an attribute have the attribute configured correctly within their recipient properties.

To establish a custom attribute that will be used by a dynamic distribution group’s Conditions setting, navigate to the Recipient Configuration container in EMC, select the Mailbox node, and select Recipient Properties for the recipient you want to configure. Select the General tab and click Custom Attributes.

You can also use PowerShell cmdlets and pipelining to create custom attributes in bulk. The Exchange Management Shell cmdlet to create a new distribution group is New-DistributionGroup; the cmdlet to create a new dynamic distribution group is New-DynamicDistributionGroup.