1 MIME: smime signed
1.1 MIME: multipart - 2 parts
1.1.1 Part 1: Content-type='text/plain' - BODY MESSAGE
1.1.1.1 WHITE_SPACES
1.1.2 Part 2: Content-type='text/plain' - Filename='pkcs7.pem'
1.1.2.1 PKCS7