I send a html email to the users using the EmailMultiAlternatives
and it worked, but the problem is in the email message the link is not working.
But when I tried doing <a href="http://127.0.0.1{% url 'add_your_details' user.username %}">
then it worked perfectly as I wanted.
template
<a href="{{ request.scheme }}://{{ request.get_host }}{% url 'add_your_details' user.username %}"
target="_blank">Add your details </a>
settings
ALLOWED_HOSTS = ['127.0.0.1']