This release allows administrators to enforce "Email only" login at the front end, while still retaining "username" logins in the back end.

Please note that in order to enable Email only logins, you must set the appropriate option in the authentication plugin and disable "Authentication - Joomla"

Anyone upgrading to this version of the authentication plugin should also upgrade to version 2.6.34 of the system plugin. This has been updated to fix a bug where an administrator could potentially prevent all access to the administration section, when they disabled the system plugin.

If you want to Enforce Email only login on the front end, then follow the steps in this Knowledge base Article