[imp] compose.php interface - compose messages from outside horde

[Martin]

Hello,

I realized one can compose a message also from another html file containing
a

<form action="<server>/imp/compose.php" enctype="multipart/form-data">

which uploads files and fields (to, subject, message) which is shown in the
composer after submitting, assumed the "Horde" Session ID is a valid one.

My problem: I want to compose a message that way from another server, e.g.
by performing a POST request via Java. As response headers I receive some
Ids (Horde, auth_key, imp_key) in the header and the HTML code from
compose.php. Then I want the browser to redirect to this message on the IMP
system. Is there a unique message ID or sth. like that which I can pass to
compose.php and then displays the previously composed message?

Or are there any other interfaces for compose.php?

Regards
Martin