How can I add a extra info on the header of the message ( see attached image). No need for custom formatting, it is fine to be exactly as "To:" and "From:".
I am developing a Zimlet in which existing emails can be associated with tracking numbers. The user will be able to associate new tracking numbers or see on that extra line if it as already been associated with a tracking number. Underlying, I am hooking a call to our webservice when onMsgView and onConvView are executed.