SMIME question

[Maya]

Hello!   I used SMIME command tool to create some SMIME messages.   I can create signed, encrypted message and to verify and decrypt them with my functions.   Now I want to make this messages fully compliant with existing mail clients: 1. My functions to can verify and decrypt message created by other mail clients. 2. Messages created by my functions to can be verifed and decripted from other mail clients (e.g Outlook Express).     When I create signed or encrypted message, I get as input param SMTP header + MIME message. Do I have to signed and encrypt both (SMTP header + MIME message) or just the second part? What should be the SMTP header of the Signed or(and) Encrypted message?   I'll be very happy If someone can help me?   Thanks Maya