Something

def composeMail (to, subject = None, body = None, cc = None, bcc = None):
      for toAddress in to:
            settextvalue ('frmComposeMessage', 'txtto', toAddress)
            if len (to) > 1:
             appendtext ('frmComposeMessage', 'txtto', ',')
    
      if subject != None:
        settextvalue ('frmComposeMessage', 'txtsubject', subject [0])
        setcontext ('frmComposeMessage', subject [0])
        
      if body != None:
        settextvalue ('frmComposeMessage', 'txtbody', body [0])

      if cc != None:
            menucheck ('frmComposeMessage','mnuView;mnuCcField')
            for toCc in cc:
             settextvalue ('frmComposeMessage', 'txtcc', toCc)
             if len (cc) > 1:
                         appendtext ('frmComposeMessage', 'txtcc', ',')
    
      if bcc != None:
             menucheck ('frmComposeMessage','mnuView;mnuBccField')
             for toBcc in bcc:
              settextvalue ('frmComposeMessage', 'txtbcc', toBcc)
             if len (bcc) > 1:
                        appendtext ('frmComposeMessage', 'txtbcc', ',')

def composeHtmlMail (to, subject = None, body = None, cc = None, bcc = None):
      menucheck ('windowName', 'mnuformat;mnuHtml')
      composeMail (to, subject, body, cc, bcc)