Java - update message headers
I'm writing a zimlet that, when invoked, stores some message headers in database.
This zimlet is made by a JSP that invokes my Java class to do the job.
All is working fine, I'm wondering now about the possibility to manage some message headers directly from this Java Class - for example, updating the message subject adding a simple prefix, just to "mark" the email.
Is there any possibility to do this via Java API calls? For example using ZMessage or ZMailBox classes, or some others?
I've searched a lot for API docs and other examples here, but I've found nothing useful for my purposes.
PS: I'm using Zimbra 7.2.4
Thanks so much.