Hello,
FYI:
Dim MyMapiMessage As MapiMessage = MapiMessage.Load(str, loadopt)
MyMapiMessage.Headers.Set("X-Mailer"...
Dim SignedMessage As MapiMessage = New Email.SecureEmailManager().AttachSignature(MyMapiMessage, MyC…...MultipartSigned , which is expected for S/MIME signing, but the loss of metadata...problem of metadata loss during S/MIME operations aligns with your...