How to allow inactive user to login?
I suggest you to keep the is active functionality and set the default value to True and create migration which will update value for currently inactive users. By following such approach you still have is active functionality, which may serve you in the moment when you will have to deactivate user.
To keep tracking on email confirmation just introduce new field is_email_confirmed and update the view which handles click on email to set that field to true.
I use a custom user model(AbstractBaseUser). How to allow inactive user to login?.  Model fields are email , active, admin,.....
By default active= false. For email confirmation activation. But I want to allow user to login both with active= true or false.