I hope this is the right place for my question?

I have opened a SR (101001757231) about the problem that Global Signatures
do not work if mails are digitally signed. The engineer informed me, that
this is working as designed. Some of the explanations don't make much sense
to me (can be my fault of course!) - that's why I would appreciate if
someone could confirm his statement.

My main question that wasn't answered: Why does S/MIME encryption work with
Global Signatures, but S/MIME signing not. For my understanding in both
cases the global signature must be added at the client level, to be included
into the text that gets encrypted or signed. Please tell me if this
reasoning is flawed.

If indeed Global Signatures do not work with digitally signed messages, I
think this should clearly stated in the documentation.

Kind regards,
Mirko Guldner