[imp] translation

[LaurentG]

Hello,

On Linux Debian 2.4.25 horde 2.2.5-2 / imp 3.2.5-1, gui still displaying 
english instead of french (fr_FR) language.

Locales are configured, fr_FR installed, gettext works.
With exported TEXTDOMAINDIR for horde, horde.mo installed for fr_FR, 
gettext doesn't work.
If I export TEXTDOMAINDIR for imp, changing nothing else, gettext works.

What did I miss with my conf files?