How can I identify number of recipients and attachment's size in ESMTP encrypted emails ?

edit

Hi I want to make statistics on my emails based on number of recipients and attachement's size. In SMTP, i can easily see mailfrom, rcpt and data commands, with email's details. My email client send encrypted emails, and everything is encrypted after Starttls command. I don't want to spy email's message or attachement, i just want to know statistics ( number of recipients & size ) : do you know how can i get theses informations in ESMTP ? ( i read RFC since days but i don't find any clue on that)