No user can login

Hi list,
I'm running Debian Woody with postgresql 7.2 to suport the web mail
horde/imp. The problem is that today at a sertein moment the web mail
start refiusing conections to the server guiving an login error message.
As far as now i check the apache-ssl the horde and the imp configuration
and all seams to be correct so i'm traying out the postgress config. I
found that the server was running aparently find but couldnt tell any
more apart from that. I need some help to check if the users are right
and could connect to the database and if they have the correct settings
and passwds. I'm acostume to work under MySQL and there you could see
the users by displaying a particular table. As i dont have much
expirience in postgresql i cant figure out how to do the same. As far
as I had read the docs there is no similar structures in postgresql, nor
could i found any command to perform the task. When i try to connect to
the server with

#psql horde hordemgr

I recive the following message

psql:FATAL 1: IDENT authentication failed for user "hordemgr"

That leads me to the posibility of having something wrong with the
database. But i lack the tools to check it.
If anyone could lead me in the trail I would be most thankfull

Cheers,
rak