Maximum incoming message size is set too high (>30MB)

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2007-02-27

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service to determine the value for the global settings delivContLength attribute located at:

CN=Configuration, CN=Services, CN=Microsoft Exchange, CN=OrganizationName, CN=Global Settings, CN=Message Delivery

If the Exchange Server Analyzer finds the value for the delivContLength attribute to be more than 30720, an error is displayed.

This error indicates that a maximum incoming message size limit is set to a value more than 30 megabytes (MB). In Exchange 2000 Server and Exchange Server 2007, there is no default message size limit. In Exchange Server 2003, the default size limit for sending and receiving messages is 10,240 KB. This default size limit applies to new installations and to upgrades from Exchange 2000 Server in which no message size limit was set.

You can conserve system resources by setting message size limits that prevent users from sending and receiving large e-mail messages. This will help limit network traffic, save disk space, and improve overall network performance. For Exchange 2000 Server and Exchange Server 2003, you can use the Defaults tab in Message Delivery Properties of your Global Settings to specify message delivery restrictions for incoming and outgoing messages. To set the maximum individual message size, select Maximum (KB), and then in the text box, type a maximum size, in kilobytes (KB). If you do not want to limit the size of messages, select No limit. Senders in your organization receive a non-delivery report (NDR) if they try to send a message to a user who goes beyond the specified size limit. Depending on the NDR settings that you configure in Internet Message Formats, external senders may not receive an NDR.

For Exchange Server 2007, you can use the Exchange Management Shell to set the TransportConfig MaxSendSize parameter for the Exchange organization.

We recommend that you set the maximum message size limit to no more than 30 MB. However, if you need a larger message size limit for messages that have large attachments to be sent through the Exchange organization, you may want to increase the maximum incoming message size limit to more than 30 MB. Increasing the message size limit over 30 MB can slow down the network performance and even cause the system to be more vulnerable to security attacks.

Though they may seem similar, the results of the following settings differs dramatically for pure Exchange 2000 Server/Exchange Server 2003 environments and Exchange Server 2007 environments.
Setting send and receive message size restrictions to a value of 0 in the Global Settings for a mailbox enabled user in a pure Exchange 2000 Server/Exchange Server 2003 environment has the effect of removing message size restrictions entirely.
Setting the TransportConfig -MaxSendSize and TransportConfig -MaxreceiveSize parameters to a value of 0 in a pure Exchange 2007 environment has the effect of restricting messages of any size from being sent.

  1. In Exchange System Manager, expand Global Settings, right-click Message Delivery, and then click Properties.

  2. In the Message Delivery Properties dialog box, on the Defaults tab, select the Receiving message size limit option and type the size limit you want.

  1. In Exchange Management Shell, run the following command where <size> is entered as the default of "unlimited" or the size in B (Bytes), KB (Kilobytes), or MB (Megabytes) in a range of 0 to 2147483647 bytes:

Set-TransportConfig -MaxReceiveSize <size>

For example, to set the maximum message size that can be received by recipients in the Exchange Organization to 10 Megabytes you would enter:

Set-TransportConfig -MaxReceiveSize 10MB

To set the maximum message size that can be received by recipients in the Exchange Organization to the default value of unlimited you would enter:

Set-TransportConfig -MaxReceiveSize unlimited

For more information about the TransportConfig cmdlet for Exchange Server 2007, see "Set-TransportConfig" in the Exchange Server 2007 Technical Reference (

  • For more information about Internet Message Formats, see "Configuring SMTP Policies to Control Outbound Mail Formatting and Automatic Responses" in the Exchange Server 2003 Administration Guide (


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