Used to indicate the options requested for the MDN receipt.
Default Value"signed-receipt-protocol=optional, pkcs7-signature; signed-receipt-micalg=optional, sha-256, sha1"
By default, the adapter will request that the MDN be signed with a PKCS#7 signature over an SHA1, SHA-256, or MD5 hash (if these algorithms are supported by the server).
Set MDNOptions to an empty string to request an unsigned receipt.
The string format is that of the Disposition-notification-options HTTP header, as specified in RFC 3335. As a form of shorthand, you may set this property to "sha1", "sha-256", or "md5" to request the indicated hash algorithm.
This property is not available in the Receiver.