seicosid
.... as some people complained about the layout and general feel of Horde's webmail GUI.
I suggest an acceptable solution to your users may be to use dimp rather than imp.
yum install --enablerepo=smecontribs smeserver-dimp
After install, when you access webmail you will see another option to select dynamic imp, try it.
If you must persist with using egroupware you can create an Alias or a redirect that points at egroupware.
You could modify the existing webmail alias or I'm sure if you do some searching on these forums you will also find suitable answers.
The code in this howto may assist you to create what you want, you will need to modify the steps/values in the howto of course.
http://wiki.contribs.org/Web_Application_Redirect_Tutorial