Topic Last Modified: 2009-03-23

When Microsoft Exchange Server 2007 Service Pack 1 (SP1)-based computers are installed in an organization, the Microsoft Exchange Server Best Practices Analyzer examines the CN=Transport Settings object in the Active Directory directory service to determine whether message restrictions are set correctly. If the Best Practices Analyzer determines that one or more message restrictions are not set according to Exchange best practices, the tool generates a best practices message, as appropriate for the particular message restriction. The message resembles the following:

The maximum incoming message size is not set. This can cause reliability problems.

The Best Practices Analyzer verifies the following message restrictions:

Earlier versions of Exchange use the CN=Message Delivery object to set message restrictions. In Exchange 2007 SP1, the information store only uses the CN=Transport Settings object to set message restrictions. This container has the following distinguished name (DN) in Active Directory:

CN=Transport Settings,CN=<organization_name>,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=contoso,DC=com

By default, incoming and outgoing message restrictions are enabled in Exchange 2007 SP1. Message restrictions that are set too low or too high may cause mail delivery issues in the organization. Also, it is best if the maximum incoming message size limit matches the maximum outgoing message size limit.

To obtain the current message restrictions in Exchange 2007 SP1, use the Get-TransportConfig cmdlet. To set message restrictions, use the Set-TransportConfig cmdlet.

The following table lists the message restriction-related properties in the CN=Transport Settings container together with the default values:

Cmdlet parameter Active Directory attribute Default value










To address this issue, use the Set-TransportConfig cmdlet to configure message restrictions.

To set message restrictions
  1. Start the Exchange Management Shell.

  2. To obtain the current message limit settings, run the following cmdlet:

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  3. Run the Set-TransportConfig cmdlet together with one of the parameters in the previous table to set the appropriate message limit. For example, to set the maximum message receive size to 6 megabytes (MB), run the following cmdlet:

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    Set-TransportConfig -MaxReceiveSize 6MB
    You must specify KB, MB, or GB in the command-line. If you do not specify one of these values, Exchange uses a value of kilobytes (KB).

For More Information

For more information about how to run the Set-TransportConfig cmdlet, run the following cmdlet:

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get-help Set-TransportConfig -detailed

For more information, see Set-TransportConfig.