ZMailMessage - Edit: Edit an existing ZMailMessage

    Fields required to edit an existing ZMailMessage instance.

    Title
        
        A textural name for the object.
        
    Subject
    
        A textural subject for the email.
    
    Date
    
        The date stamped on the email (textural or DateTime object).
    
    To
    
        Textural information on who the email was sent to.
        
        Usually in the format of an email address.
    
    Sender
    
        Textural information on who the email was sent by.
    
        Usually in the format of an email address.

    ReplyTo
    
        Textural information on who to send your reply to
        (if different from the to address).
    
        Usually in the format of an email address.
    
    Body
    
        The body of the email message.
    
    Headers
    
        All the headers from the email message, including the ones above,
        in a dictionary of {'headerName':'value'}.