Help with S/MIME illustration

Hi, I’am trying to illustrate complete process of sending message encrypted by S/MIME with triple-encapsulation.

Here is the illustration that I have done.

Please comment. I think I am missing something out.
Any help will be greatly appreciated!

I’m not an expert on this topic, but I assume you are attempting to implement this?

Thanks for reply.
This realy is described in that RFC2634, but it is not very clear what is happening in each stage and what is the output of each stage.
I couldn’t find a single detailed illustration of S/MIME on the internet.
On the other hand, processes of PGP are illustrated in detail on many sites.

Someone please help with.