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On March 10th 2020 Microsoft recommends to move to LDAP channel binding and LDAP signing to avoid replay attacks on the LDAP communication.After the hardening changes are done, Simple Authentication and Security Layer (SASL) LDAP binds that do not request signing (integrity verification) will be rejected by Active Directory domain controllers.Sophos Email Appliance supports LDAP authentication over SSL/TLS to avoid man-in-the-middle attacks.
Please refer to the below article for more information: