LDAP auth using email address

Having issues configuring to have LDAP users login with email address.

I have used the ldap-check.sh utility so that the user is located vi email
e.g…/ldap-check.sh -u user_@_example.com

ldapsearch -LLL -x -h ldap.example.com -p 389 -D “cn=Directory Manager” -w “passsss” -b “o=domain” “(mail=user_@_example.com)” mail uid mail

this provides the expected result, but the login fails. I need to have LDAP users auth as the email address only.

Can someone please help me get this configured?