From ba302ba66e88942841281c984a6b31ca6d6289e6 Mon Sep 17 00:00:00 2001
From: Spiros Kalogeropoulos <37223501+KaSpiros@users.noreply.github.com>
Date: Fri, 27 Feb 2026 12:38:27 +0000
Subject: [PATCH] Add support for custom email headers via JSON input (#264)

* Adding custom header with JSON support

* Adding headers in test workflow

---------

Co-authored-by: W506810_wexinc <spiros.kalogeropoulos@wexinc.com>
---
 .github/workflows/test.yml | 1 +
 README.md                  | 2 ++
 action.yml                 | 3 +++
 main.js                    | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index c1cf2b81..017ff877 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -46,6 +46,7 @@ jobs:
           convert_markdown: true
           attachments: package.json,action.yml
           priority: high
+          headers: '{"X-My-Test-Header": "Passed"}'
 
       - name: Get mail
         run: |
diff --git a/README.md b/README.md
index b490e95d..a8b2f660 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,8 @@ Some features:
     attachments: attachments.zip,git.diff,./dist/static/*.js
     # Optional priority: 'high', 'normal' (default) or 'low'
     priority: low
+    # Optional custom headers:
+    headers: '{"X-Priority": "3 (Normal)", "X-My-Header": "MyValue"}'
     # Optional nodemailerlog: true/false
     nodemailerlog: false
     # Optional nodemailerdebug: true/false if true lognodem will also be set true
diff --git a/action.yml b/action.yml
index 51172389..30945651 100644
--- a/action.yml
+++ b/action.yml
@@ -57,6 +57,9 @@ inputs:
   priority:
     description: Set Priority level for the mail message to 'high', 'normal' (default) or 'low'
     required: false
+  headers:
+    description: 'Custom headers for the mail message as a JSON string (e.g., {"X-Custom-Header": "value"})'
+    required: false
   nodemailerlog:
     description: Log option for nodemailer
     required: false
diff --git a/main.js b/main.js
index 6a557333..976dd939 100644
--- a/main.js
+++ b/main.js
@@ -115,6 +115,7 @@ async function main() {
             required: false,
         });
         const envelopeTo = core.getInput("envelope_to", { required: false });
+        const headers = core.getInput("headers", { required: false });
 
         // if neither to, cc or bcc is provided, throw error
         if (!to && !cc && !bcc) {
@@ -166,6 +167,7 @@ async function main() {
                         ? getText(htmlBody, convertMarkdown)
                         : undefined,
                     priority: priority ? priority : undefined,
+                    headers: headers ? JSON.parse(headers) : undefined,
                     attachments: attachments
                         ? await getAttachments(attachments)
                         : undefined,