How do I send a Django email with a custom From header?

[YPCrumble]

I'm attempting to set a different MAIL_FROM and From header in Django so that I can use a custom bounce domain. Django allows this by setting the bounce domain as the email's self.from_email attribute, and overriding the From header manually.

However, this yields the Sparkpost API error pasted below. I'm using Django Anymail 1.3 with python-sparkpost 1.3.5. Any suggestions would be tremendous!

Sending a message to test@example.com from mail@bounces.example.com
SparkPost API response 422: Unprocessable Entity
{
  "errors": [
    {
      "message": "Invalid header",
      "description": "Error while validating header From: 'From' header must be specified in content.from.name and content.from.email",
      "code": "3002"
    }
  ]
}

[YPCrumble]

Update - it looks like the way this library constructs the from_email differs from how Django constructs the from_email attribute. Django first looks for From in its extra_headers attribute, while this library takes the from_email without allowing the override.

I'd be happy to submit a PR if that's helpful. I could also potentially understand suggesting that I add a custom return_path to Anymail's esp_extra dictionary, which I believe would adjust the currently undocumented return_path parameter on the transmissions.send method. Happy to add a PR to document return_path here if that's helpful instead: http://python-sparkpost.readthedocs.io/en/latest/api/transmissions.html?highlight=transactional#sparkpost.transmissions.Transmissions.send

[jgzamora]

@YPCrumble awesome work digging up all the parts of this issue! I will document return_path for this lib and check if there are any other params that need documenting. It looks like your use case is currently possible, so I'm going close this issue. If you still still think we should update to better match how Django does this, please create another issue so we can discuss it in more detail.