My problem was that I need to create the account on zimbra before log in. I did this
echo "ca email@example.com ''" | /opt/zimbra/bin/zmprov
This create the account on zimbra, zimbra first test if the account exists on It's ldap server and then verify password on the external LDAP.
I will let the original post for admins tha could have the same problem.
I've installed Zimbra Version 4.5.8_GA_1394.DEBIAN3.1 02-oct-2007
Everything works fine but when I try to configure an external LDAP for authenticate one of my virtual domains.
I followed the instructions and the initial configuration worked ok, it connects to the external LDAP and the user test was successfilly. Test was ok but user authentication fails.
My external LDAP is on the same server but listening on a different port (3890).
If I dump network connections on "lo" interface I don't see any connection to 127.0.0.1:3890, it is for 127.0.1.1:389, so it never try to contact the external LDAP to do te validation.