Ticket Reference:

http://helpdesk.spamtitan.com/support/tickets/21781


If a customer changes/upgrades the Windows Server Domain Controls, and LDAP Stops working, the reason cloud be the following

It appears in the 2008 PDC the default setting is for only secure queries. 
We changine the setting to 'none', which will accept both secure and non-secure requests should fix the issue:

Refern:


If you ever want to go the secure route for LDAP Authentication/Recipient Verification/SASL/Quarantine > Aliases 

(i.e. LDAPS://)  note the following:


- The host for secure LDAP uses the urls, not the IP, it usually looks like ldaps://{ldap server FQDN}

- The port is 636, not the default of 389