[horde] Disable IMP for users without IMAP mailboxes

[Aaron E. Klemm]

Hello,

Is there a way to disable IMP for users without mailboxes?

Our situation:
Using composite authentication off our imap server which itself
authenticates off ldap. We have a subset of users who should have access
to most of our websites--the various webapps authenticate off
ldap--including everything in Horde except for IMP (they aren't a class
of users that we provide email to). 

Currently they login to Horde successfully because IMAP authenticates
them off ldap without a problem even though we haven't created
mailboxes. We want it this way so users can access other Horde tools,
but they are getting very confused when they can see an email interface
and can send messages, but cannot receive them.

Would using LDAP exclusively for authentication solve the whole problem?
If so, how does LDAP auth pass on credentials to IMAP?

Thanks for you help,

Aaron Klemm