Microsoft KB Archive/812298

= Mail delivery is slow after you configure delivery restrictions that are based on a distribution list =

Article ID: 812298

Article Last Modified on 10/25/2007

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APPLIES TO


 * Microsoft Exchange Server 2003 Enterprise Edition
 * Microsoft Exchange Server 2003 Standard Edition
 * Microsoft Exchange 2000 Enterprise Server
 * Microsoft Exchange 2000 Server Standard Edition

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SYMPTOMS
If the following conditions exist, inbound and outbound mail delivery may be slower than you expect:
 * You configure delivery restrictions on a Simple Mail Transfer Protocol (SMTP) connector.
 * By default, your restrictions are set so that messages from everyone are rejected.
 * You add distribution lists to the Accept messages from list.



CAUSE
This problem occurs because Exchange Server must expand the distribution lists to determine whether each user account is permitted to send or to receive the e-mail message. Also, the results of this distribution list-expansion are not cached by Exchange Server.



WORKAROUND
To work around this problem, use one of the following methods.

Method 1: Limit the Use of this Delivery Restriction
Try to limit the number of servers that use this kind of delivery restriction. If you can, enable this kind of delivery restriction only on source bridgehead servers in your organization. If you can limit this to only certain bridgehead servers, try to dedicate a global catalog (GC) server to each of these bridgehead servers.

Method 2: Use User-Based Delivery Restrictions
Add the specific user accounts to the Accept messages from list instead of using distribution lists. This increases performance because whereas Exchange Server does not cache the results of the expanded distribution list, it does cache the results of delivery restrictions that are based on individual user accounts. This method works when you want to add up to 1,000 user accounts. However, if you want to accept messages from more than 1,000 users, create additional SMTP connectors. You must make sure that each is identically configured, and then add up to 1,000 user accounts to the Accept messages from box on each connector.

Important Make sure that each SMTP connector is assigned the same cost. Otherwise, Exchange Server queries only the first SMTP connector, and returns a non-delivery report (NDR) if the user account is not listed in the Accept messages from list of that connector. For more information about another solution that is available if you are running Microsoft Exchange Server 2003 Service Pack 2 or a later verion of Exchange Server 2003, click the following article number to view the article in the Microsoft Knowledge Base:

895407 In Exchange Server 2003, message delivery to local mailboxes and to external mailboxes is slower than you expect after you configure delivery restrictions based on distribution groups



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.



MORE INFORMATION
For more information about how to enable a distribution list-based restriction to a connector, click the following article number to view the article in the Microsoft Knowledge Base:

277872 Connector delivery restrictions may not work correctly

Additional query words: XADM

Keywords: kbtransport kbnofix kbbug kbprb KB812298

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