Hello John,
probably you tried it already, but why don't you configure two message mappings?
1.- One for the messages that have the status A, B or C
2.- One for the messages that have any other status. This last mapping should produce an xml similar to the following:
<ns:Mail xmlns:ns="http://sap.com/xi/XI/Mail/30">
<Subject>Subject</Subject>
<From>namea@company.com</From>
<To>nameb@company.com</To>
<Reply_To />
<Content_Type>text/plain</Content_Type>
<Content>
This is the content.
</Content>
</ns:Mail>
In your ICO or Interface Determination you can create two conditions:
1.- One for the messages that have the status A, B or C
2.- One for the messages that have any other status.
And depending on the condition, you execute one mapping or another. Finally you can use a Soap Receiver Channel to send "normal" messages and the email adapter to send "error" messages.
Please, check the following links for further information:
Configuring the Receiver Mail Adapter (SAP Library - Partner Connectivity Kit)
XI/PI: Sending Emails Using XI Mail Adapter
I hope it helps!
Regards!