How to use Mailgun's recipient-variables with Django SMTP mail backend?

How can I properly send batch/bulk/mass emails using MailGun in Django using SMTP protocol?

What I've tried so far?

• I am using django.core.mail.backends.smtp.EmailBackend as my EMAIL_BACKEND

and this is the code snippet that I have tried to send the emails.

from django.core.mail import EmailMultiAlternatives
import json

to_emails = [
    "mail_1@example.com",
    "mail_2@example.com",
    "mail_3@example.com",
    "mail_4@example.com",
    "jerinpetergeorge@gmail.com",
]
mail = EmailMultiAlternatives(
    subject="Hey - %recipient.name%",
    body="Hey %recipient.name%,\n\nThis is just a batch email test!!!",
    from_email="JPG <me@somehost.com>",
    to=to_emails,
)
recipient_variables = {
    address: {"name": address} for address in to_emails
}
mail.extra_headers["X-Mailgun-Recipient-Variables"] = json.dumps(recipient_variables)
response = mail.send()
print(response)

and I've got the mail as below,

As we can see, the to attribute is filled with all email addresses, which is not what I am expecting.

So, how can I tell the Mailgun/Django to parse my variables properly in order to make the emails looks more personal?

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Notes

• I prefer to use SMTP protocol
• I've tried the REST APIs of Mailgun and it was a success (but, I prefer SMTP)
• I found django-anymail and seems it has the feature. But, It also uses the APIs (correct me if I am wrong)

---

Update-1

• Updated the to argument to to="%recipient%" But, got

  • TypeError: "to" argument must be a list or tuple

• Updated the to argument to to=["%recipient%"] But, got

  • smtplib.SMTPRecipientsRefused: {'=?utf-8?q?=25recipient=25?=': (501, b'Invalid command or cannot parse to address')}

from How to use Mailgun's recipient-variables with Django SMTP mail backend?