[imp] IMP Transparent login

[adam]

Hello,
I've been reading the list and decided to post, not finding the answer I 
need.  I'm working with the latest stable IMP and horde, and I have 
an irritating requirement.  All of our users are stored in an x.500 
directory, with an LDAP interface.  These users are spread among multiple mail 
servers, but their X.500 password is kept in sync with their preferred server. 
I am trying to setup imp in such a way that when the user authenticates to 
horde, via ldap, their preferred server is pulled out,
and they are transparently authenticated to IMP.
I have added the proper code to Auth/ldap.php to get the server, 
but I am having trouble getting them to authenticate.

It was reccomended that I do :

  $res = $registry->callByPackage('imp', 'authenticate',
                                     array('userID' => $userID,
                                           'credentials' => $credentials,
                                           'params' => array('server' => 
$server)));

But I get a non-object error with this piece of code in place.
Am I barking up the wrong tree?
Thanks,
Adam

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