Article ID: 273233 - View products that this article applies to.
This article was previously published under Q273233
You cannot modify MAPI messages that are trapped in a Simple Mail Transfer Protocol (SMTP) transport event sink, such as one that implements the ISMTPOnArrival::OnArrival method. Any modifications made to these messages seem to be successful, and show up in the scope of the event sink, but do not persist to the actual message. Additionally, some properties, such as attachments and the message's body, may not be available.
SMTP transport event sinks for Exchange 2003 or Exchange 2000 can be used to trap all outgoing e-mail messages as they are handled by the SMTP transport layer. The cause of this problem is that Exchange converts MAPI messages to a temporary SMTP version for the event sink to handle, and then discards this temporary version after the event sink code finishes executing.
The key to the problem is how the message arrives at the Exchange server. A MAPI message can arrive at the Exchange server in the following ways:
317680For more information about how to force outbound messages through a border Exchange server or through a smart host, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/317680/ )How to add a disclaimer to outgoing SMTP messages in Visual Basic Script
293800For more information about how to configure the SMTP connector, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/293800/ )How to set up Windows 2000 as an SMTP relay server or smart host
(http://support.microsoft.com/kb/265293/ )How to configure the SMTP connector in Exchange
Though this limitation is inherent to Exchange 2003 and Exchange 2000, it can be observed through the Windows SMTP Transport Event Sinks as well: