In Microsoft Exchange Server 2007, you send an e-mail message that has the Request a Delivery Receipt option enabled. When you do this, the recipient information in the body of the message incorrectly contains the character string "%40" in the address instead of the at sign (@).

Additionally, you may receive a delivery status notification (DSN) message that resembles the following DSN message:Note In this example, the recipient address should be "user01@contoso.com."

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This problem occurs if you change the settings of the Exchange Server 2007 transport server to send a DSN message in plain text format. When you do this, the transport server generates a plain text DSN message that treats the at sign (@) as an escape character. Therefore, the at sign is replaced by the character string "%40."

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Service pack information

Exchange Server 2007 Service Pack 1 (SP1) was released on November 29, 2007.

To obtain Exchange Server 2007 Service Pack 1 (SP1), visit the following Microsoft Web site: For more information about the fixes that are included in Exchange Server 2007 Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base:

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Update Rollup information

To resolve this problem, install Update Rollup 5 for Exchange Server 2007. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

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This problem was first corrected in Exchange Server 2007 Service Pack 1.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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To send a DSN message in plain text format, run the following command in the Exchange Management Shell: For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

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