What Are LDAP Searches?
When the starting addresses https://servername or https://servername/exchange are used, a query is performed against Active Directory of the current domain to find the available mailboxes. The results should reflect all the users in the Active Directory who own a mailbox. Depending on the configuration of Active Directory, it is possible that the results do not match the anticipated results.
You can use the LDAPSearchRoot and LDAPFilters hidden advanced parameters of the Microsoft Exchange connector to fine tune the search (see Modifying Hidden Microsoft Exchange Source Parameters).
Example: In the following LDAP search example that could be used for the LDAPSearchRoot parameter, the first part of the LDAP string is important, since it specifies the domain.