[Django]-Setting up Django with Redis, Celery to send emails via Gmail

This error isn’t anything to do with email. Celery is trying to connect to a message broker via the amqp protocol, which implies RabbitMQ; but you say you have set up Redis as the broker. So Celery is not picking up that setting.

The reason for this is that you need to prefix the Celery-specific settings with CELERY_ in your settings.py; so BROKER_URL should be CELERY_BROKER_URL.