The S/MIME Message Specification (8/29/95) does not speak to content transfer encodings when using multipart/alternative. So, either it is encoded, which may result in an unreadable message if an opaque encoding (base64) is chosen, or it may result in a clear-text message that does not correspond exactly to the signed message if no encoding is used. If quoted printable is used for email that might not otherwise make it through the network unscathed, the message will be readable and will emerge at the other end of the pipe intact.Your concern that a message might not make it through the network "unscathed" is the same one I have about MOSS. Doesn't MOSS compute the signature on the *encoded* data, the same data that won't make it through unscathed?
You ommitted the last sentence of my paragraph:
Of course, MOSS will provide the same result with a message that is less than half the size.
The context was discussion of the usefulness of S/MIME with multipart/alternative versus MOSS for non-MIME and non-security (no S/MIME or MOSS) aware user agents. The point that I was trying to make is that quoted printable encoding may be necessary to protect any message text from inadvertent changes en route while still keeping it readable in the raw. Given that the S/MIME alternative will require the same encoding as the MOSS signed body part if it is to make it through the network unscathed, S/MIME gains you nothing in this respect except a message twice the size and a potential for additional ambiguity with respect to what is signed and what you are reading. Mark
binMApNvWTKwp.bin
Description: application/moss-signature