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Extended support for custom headers: Paubox Email API

Written by Hoala Greevy | May 08, 2025

Yesterday we covered how to integrate Paubox SMTP API, our HIPAA compliant transactional email solution with WordPress. 

Today, we're pleased to announce expanded support for custom headers for Paubox Email API. This post will explain what's covered in this release.

 

Custom headers for Paubox Email API

As a recap, in December, we announced support for custom headers in Paubox Email API.

In short, it's done via an optional data parameter string:

X-<Custom-Header-Name>

See below:

 

Custom headers for Messages endpoint

With today's release, custom headers are also present in the success response of the Messages endpoint of Paubox Email API. 

Here's a screenshot:

 

Webhook payloads now support custom headers

Paubox Email API supports four types of webhook events:

  • Delivered
  • Temporary Failure
  • Permanent Failure
  • Opened

Custom headers are now supported in the payload of each event when subscribed to a webhook.

Here's an example:

 

Secure Message Center custom header

If you have an onerous compliance requirement that (incorrectly) requires all secure email to be read via a secure link and web browser, you can insert this custom header to achieve that result:

X-Force-Secure-Msg

See also: Quickstart guide for Paubox Email API

 

Conclusion

Extended support for custom headers in Paubox Email API yields additional granularity and reporting for developers seeking a HIPAA compliant transactional email solution.

Send up to 300 emails per month for free with Paubox Email API. Business associate agreement (BAA) included.

 

See also: Paubox SMTP API: Everything you need to know

See also: Click and open tracking added to Paubox Email API