As suggested in the comments you need to implement a task queue and worker. In my projects I use django-rq and Redis.
See the repo here: https://github.com/rq/django-rq
Then you can push the send_mail function into the queue as shown in the example:
import django_rq # process stuff here # queue the email for sending django_rq.enqueue(send_mail, subject, plain_message, from_email, [order.customer.email], html_message=html_message)
But make sure that you’ll need to also have a worker in the background to actually process the items in the queue.
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