When configuring the connector, make sure that the value mapped to the email attribute matches the existing Zendesk user's email address exactly as it appears in Zendesk.

For example, on the Attribute Mapping tab, the user's email attribute on Zendesk is mapped to the user mail attribute in your LDAP. This will synchronize a user that already exists on Zendesk with an email address in Zendesk of john.smith@mydomain.com. In this case, the user's mail attribute in LDAP would also have to be john.smith@mydomain.com.

When the Zendesk connector provisions for the first time, this address is used to synchronize the user in your LDAP data store with the user in Zendesk.