[otrs] CustomerAuth against Exchange 5.5

Hello, at the moment, I authenticate Customers against an Exchange 5.5 via LDAP. This Exchange replicates with an other one. Therefore its essential (for me) to change BaseDN depending on the Username (customer.pl). Example: Customer from OfficeA enters "OfficeA/username" Customer from OfficeB enters "OfficeB/username" But for this to work, something has to change inside any of the LDAP.pm I suppose. I'm no Perl-hacker, so probably someone can help here? Thanks alot and regards Wolfgang