Thunderbird extention for signing messages

I have: 40 client machines using mail through Mozilla Thunderbird by IMAP. It is required to develop an extention for implementation in each mail client: Extention functions: 1) the addon should work before sending each message via IMAP or via SMTP, modifying the email sent. 2) Generating a unique id of an outgoing message (15-character random row [0-9a-zA-Z]) 3) Insert this id into the header of the email to be sent. "Tdf-ID: {id}" 3a) If message allready has "Tdf-ID: {id}" headers -> replace it (happens when multitime reply on email) 4) In the body of the letter to embed the image <img src ="[login to view URL]{id}"> 5) Modify all the links (for a specific domains like [login to view URL], [login to view URL], etc.) in the body by set GET parameters: Http://[login to view URL] -> [login to view URL]{id} Http://[login to view URL] -> [login to view URL]{id} 5a) If message allready has this GET params -> replace it