Hello,

We can add a dynamic distribution group to "Message Delivery Restrictions" in Exchange 2010 but what i worry about that is performance. Is that cause a problem in a big organization (more than 1 million daily mail traffic)?

It's a good solution for a group to restrict receiving mails from everywhere. but it may cause performance problem if we generalize for more mail groups or mailboxes. Because when i add a dynamic group, mails delay more than normally.

Thanks in advance.

Hi Ebubekir V,

Dynamic Groups does add an overhead to the server.

For Transport Rules:- By default, the Expanded Groups Cache stores group membership for four hours. Recipients returned by the recipient filter of a dynamic distribution group are also stored. The Expanded Groups Cache makes repeated round-trips to Active Directory and the resulting network traffic from resolving group memberships unnecessary.

NOTE:- The Expanded Groups Cache isn't used by the categorizer to resolve recipients for message delivery.

• Try setting the ExpansionServer parameter set on the group, to target a free less loaded server for DL expansion.

If the sender isn't found in either parameter, the distribution groups in those parameters are fully expanded. This complete expansion of distribution groups may take some time. We recommend that you minimize the depth of nested distribution groups in those parameters.

Optimal Performance

Over at Outlook Live Answers weve just published some new guidance about the best way to configure dynamic distribution groups for optimal performance, including how to make use of the new multi-value custom attributes.

• Use message tracking to identify the nodes between which you have the delay.
• You might want to setup performance monitoring on Exchange, AD server with and without DDG in place.
• Alternetly you might "Hide the DL from GAL" to avoid unwanted users sending emails to it.

References:

How to Troubleshoot Query-Based Distribution Groups

Recipient resoluti