Hook Needed

Dear Sir

Thank you for this awesome plugin
Every Email sent gets a random Message ID. There is no hook in the plugin to be able to customize Message ID to our needs. Every Message ID changes for every email sent. In case I want to customize this for my helpdesk based on subject, Ticket Number, Sender, Recipient…etc.. so that that message appears in a single thread – I am unable to do so because of the unavailability of an appropriate hook – Can you throw some light on this please
So if you give us some appropriate hook or any other option so we are able to integrate this excellent plugin with other plugins which need to send notifications in a structured manner as per their need.