[imp] Zero-length attachments

[Roger B.A. Klorese]

> From CVS HEAD of horde/imp/docs/INSTALL:
> 
>       ** If this is a new install, you will not be able to configure
>          IMP using the Horde Administration/Configuration tool if you
>          first enabled IMP authentication for Horde. You must 
> set Horde
>          to use another authentication method, configure IMP, 
> then reset
>          Horde to use IMP authentication.


That's a good location for it.

A better one would be in the Horde INSTALL file, as well as directly in
the horde/conf.php file where the example of IMP authentication is
given.