[imp] advice please - my links or buttons to accept/decline event are missing from event invitations in imp.

[gimili]

My links or buttons to accept event invitations are no longer showing in 
the recipients emails when using imp.  My os is debian lenny.  I have 
tried firefox 3.5.2 and internet explorer 7.  I originally thought the 
links were not showing in thunderbird but I was mistaken.  Thunderbird 
with lightning extension seems to be working really well.

I originally posted to kronolith list but I now think my problem is in 
imp or maybe something needs to be tweaked in debian.

Any help or advice much appreciated!

-- 
gimili