A directory to hold information used for asynchronous receipt verification.
This setting specifies a directory which holds information about the original message that was sent.
When sending files and requesting asynchronous receipts set this directory to a location where data can be stored. When the receipt is later received this property should be set so original message information can be read in order to verify the receipt.
As an alternative the original message information may be manually stored by saving the values of OriginalSOAPMessage and OriginalSOAPMessageId after sending a file. In this case OriginalSOAPMessage and OriginalSOAPMessageId should be populated before verifying the receipt.