Some time ago, my company switched over to using Internet Site documents to configure Internet protocols, including LDAP. I’m guessing they also changed our LDAP server to only accept authenticated connections at the same time. (This is, by the way, a really good idea.)
Not wanting to use the company-supported Outlook or Express (for obvious reasons), I use Mozilla Thunderbird, so I provide my own support. I had figured out that for tbird to work with Domino LDAP, the search filter in the LDAP directory advanced tab has to be (cn=). Well, maybe there are others, but the default (objectclass=) entry didn’t work. After the change to Internet Site docs, this no longer worked.
Finally, I figured out that the problem was authentication (tbird still doesn’t do well at telling you what went wrong with LDAP). I needed to supply a username/password, but didn’t see where I could do this. The only fields I saw to investigate were Base DN and Bind DN. Not being an LDAP maven, I didn’t realize that Bind DN is LDAP “secret code” for … username!
Still, though, you have to enter it the right way. In my case, it was cn=Kent Pilkington,0=HHOMES. The first is obviously my name (cn means Common Name), and HHOMES is the Notes domain that I belong to. If your company has a more complex hierarchy, then you might need to use something different. In any case, if you look up your name in the ($LDAPCN) view of the public address book, get the value in the %DN column (Distinguished Name), replace the /'s with ,'s, then you have your Bind DN.
Once Thunderbird sees that you have a Bind DN, it will propt you for a password and assuming all other things work, you’ve got directory!
Happy hunting.