[Dovecot] Operations error with AD connections

[Maarten Vanraes]

Hello,

dovecot version: 1.0.beta3-3ubuntu5.5
OS: 2.6.15-26-server i686 GNU/Linux Ubuntu dapper
filesys: ext3
authentication is with ldap (Active Directory)

the problem is that after a while with a number of pop3 connections (8 people 
who have checking every 5 minutes), the ldap_search gives 'Operation Error' . 
we have tried to use the global catalog, but that doesn't solve the problem. 
the binding is the problem, we must use binding, cause we don't get a 
userPassword field.

Right now, we have switched to courierLDAP and it works for now, we'll have to 
see if it persists (we have set an LDAP timeout variable, but don't know if 
it's related.) The thing is that we have lots of places where can setup 
something like this with AD, and that for now, we'll probably use courier.

dovecot-ldap.conf:

hosts = 172.17.80.1:3268
dn = CN=SPIC,OU=Beheerders,OU=Zonnegroep,DC=zonnewende,DC=local
dnpass = xxxxxxxxx
auth_bind = yes
ldap_version = 3
base = dc=zonnewende, dc=local
user_filter = (mail=%u)
pass_attrs = uid=user,userPassword=password
pass_filter = (mail=%u)
user_global_uid = 5000
user_global_gid = 5000

any ideas on how to solve it?

PS: can you CC me?
-- 
Maarten Vanraes
BA NV: IT & Security