Represents a MailMessage in the central backlog.
The BacklogMessage is the proposed answer for the corresponding
IncomingMessage of that Ticket.
It is build using a Template, that defines the subject, text and attachments
for the proposed answer including the original IncomingMessage
During its lifecycle a BacklogMessage can be modified several times
by an agent. Every change will be stored in the message archive.
Methods inherited from interface com.novomind.ecom.api.imail.model.MailMessage