When you send an email message to a Microsoft Exchange Server 2007 user, you may receive a Non Delivery Report (NDR) which contains the following information:
554 5.6.0 STOREDRV.Deliver; Corrupt message contentHowever, you can send other email messages to the same user successfully during the same period.
This problem occurs when the email message is a multipart/mixed MIME message which contains a text/plain body and an application/applefile body. If the corresponding body is not a real application/applefile body, the Exchange Server 2007 server considers that the email message is invalid. Therefore, it generates the NDR. However, Exchange Server 2010 can deliver this kind of email message successfully.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.