[imp] Login in IMP needs an additional auth

[Frank Kirschner]

Hello Firends,

working with Horde Groupware Webmail Edition 4.0.8 and IMP 5.0.23.
After login in Horde, it's shown the error:

User is not authorized for imp 

Then I click on left side on webmail. The login page is showing again and
after login, I'm directly in IMP and after goin back to the Horde portal,
the webmail menue tree is fully shown and active.

What do I have to configer in IMP to take over the login from the Horde
login?

best regards
Frank