I am writing to request a new feature that would enhance the functionality of Mailgun's Bulk Sending API. Currently, while Bulk Sending allows for efficient email delivery to multiple recipients, it lacks the ability to set custom headers for each recipient individually.

Here's the scenario I'm facing:

• I want to send a bulk email campaign to a list of customers.
• While the email content might be similar, I need to include different custom headers for each recipient (e.g., X-Customer-ID, X-Campaign-ID).

Proposed Feature:

I would like to propose the addition of a mechanism to incorporate custom headers for each recipient within the Bulk Sending API. This could be achieved by:

• Allowing the inclusion of custom header data alongside standard data in the CSV file used for bulk sending.
• Introducing a new field prefix (e.g., recipient_) within the CSV file to denote custom headers for each recipient.
• Leveraging existing recipient variables functionality within the template to dynamically insert custom header values from the CSV file.

Benefits:

This feature would offer significant benefits for users like myself by:

• Enabling targeted email campaigns with personalized headers for each recipient.
• Streamlining the process of sending bulk emails with custom data points.
• Increasing the flexibility and functionality of the Mailgun Bulk Sending API.

I believe this feature would be valuable for a wide range of Mailgun users who require a balance between bulk sending efficiency and recipient-specific customization.