Exchange linked mailboxes not authenticating with ESP and Alternative SSO enabled


when setting this up to pass authentication to a trusted SSO domain authentication does not work.
the ldap server for the trusted domain is set to the main domain controllers.

however any authentication requests are failing immediately i could not find any detail in the documentation about this.

if bypassing the loadbalancer, logging directly into the server results in a successful login.


the closest case of a similar issue was in this post: