diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c63a098..908f93f7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## 4.3.0 2017-10-23
+
+- Added new mail object method `mail.normalize(cb)` that should make creating HTTP API based transports much easier
+
 ## 4.2.0 2017-10-13
 
 - Expose streamed messages size and timers in info response
diff --git a/lib/json-transport/index.js b/lib/json-transport/index.js
index 1d0969ce..d00597ed 100644
--- a/lib/json-transport/index.js
+++ b/lib/json-transport/index.js
@@ -57,7 +57,7 @@ class JSONTransport {
         );
 
         setImmediate(() => {
-            mail.resolveAll((err, data) => {
+            mail.normalize((err, data) => {
                 if (err) {
                     this.logger.error(
                         {
@@ -72,43 +72,11 @@ class JSONTransport {
                     return done(err);
                 }
 
-                data.messageId = messageId;
-
-                ['html', 'text', 'watchHtml'].forEach(key => {
-                    if (data[key] && data[key].content) {
-                        if (typeof data[key].content === 'string') {
-                            data[key] = data[key].content;
-                        } else if (Buffer.isBuffer(data[key].content)) {
-                            data[key] = data[key].content.toString();
-                        }
-                    }
-                });
-
-                if (data.icalEvent && Buffer.isBuffer(data.icalEvent.content)) {
-                    data.icalEvent.content = data.icalEvent.content.toString('base64');
-                    data.icalEvent.encoding = 'base64';
-                }
-
-                if (data.alternatives && data.alternatives.length) {
-                    data.alternatives.forEach(alternative => {
-                        if (alternative && alternative.content && Buffer.isBuffer(alternative.content)) {
-                            alternative.content = alternative.content.toString('base64');
-                            alternative.encoding = 'base64';
-                        }
-                    });
-                }
-
-                if (data.attachments && data.attachments.length) {
-                    data.attachments.forEach(attachment => {
-                        if (attachment && attachment.content && Buffer.isBuffer(attachment.content)) {
-                            attachment.content = attachment.content.toString('base64');
-                            attachment.encoding = 'base64';
-                        }
-                    });
-                }
+                delete data.envelope;
+                delete data.normalizedHeaders;
 
                 return done(null, {
-                    envelope: mail.data.envelope || mail.message.getEnvelope(),
+                    envelope,
                     messageId,
                     message: JSON.stringify(data)
                 });
diff --git a/lib/mailer/mail-message.js b/lib/mailer/mail-message.js
index 6bfb443f..a51a970f 100644
--- a/lib/mailer/mail-message.js
+++ b/lib/mailer/mail-message.js
@@ -135,6 +135,82 @@ class MailMessage {
         setImmediate(() => resolveNext());
     }
 
+    normalize(callback) {
+        let envelope = this.data.envelope || this.message.getEnvelope();
+        let messageId = this.message.messageId();
+
+        this.resolveAll((err, data) => {
+            if (err) {
+                return callback(err);
+            }
+
+            data.envelope = envelope;
+            data.messageId = messageId;
+
+            ['html', 'text', 'watchHtml'].forEach(key => {
+                if (data[key] && data[key].content) {
+                    if (typeof data[key].content === 'string') {
+                        data[key] = data[key].content;
+                    } else if (Buffer.isBuffer(data[key].content)) {
+                        data[key] = data[key].content.toString();
+                    }
+                }
+            });
+
+            if (data.icalEvent && Buffer.isBuffer(data.icalEvent.content)) {
+                data.icalEvent.content = data.icalEvent.content.toString('base64');
+                data.icalEvent.encoding = 'base64';
+            }
+
+            if (data.alternatives && data.alternatives.length) {
+                data.alternatives.forEach(alternative => {
+                    if (alternative && alternative.content && Buffer.isBuffer(alternative.content)) {
+                        alternative.content = alternative.content.toString('base64');
+                        alternative.encoding = 'base64';
+                    }
+                });
+            }
+
+            if (data.attachments && data.attachments.length) {
+                data.attachments.forEach(attachment => {
+                    if (attachment && attachment.content && Buffer.isBuffer(attachment.content)) {
+                        attachment.content = attachment.content.toString('base64');
+                        attachment.encoding = 'base64';
+                    }
+                });
+            }
+
+            data.normalizedHeaders = {};
+            Object.keys(data.headers || {}).forEach(key => {
+                let value = [].concat(data.headers[key] || []).shift();
+                value = (value && value.value) || value;
+                if (value) {
+                    if (['references', 'in-reply-to', 'message-id', 'content-id'].includes(key)) {
+                        value = this.message._encodeHeaderValue(key, value);
+                    }
+                    data.normalizedHeaders[key] = value;
+                }
+            });
+
+            if (data.list && typeof data.list === 'object') {
+                let listHeaders = this._getListHeaders(data.list);
+                listHeaders.forEach(entry => {
+                    data.normalizedHeaders[entry.key] = entry.value.map(val => (val && val.value) || val).join(', ');
+                });
+            }
+
+            if (data.references) {
+                data.normalizedHeaders.references = this.message._encodeHeaderValue('references', data.references);
+            }
+
+            if (data.inReplyTo) {
+                data.normalizedHeaders['in-reply-to'] = this.message._encodeHeaderValue('in-reply-to', data.inReplyTo);
+            }
+
+            return callback(null, data);
+        });
+    }
+
     setMailerHeader() {
         if (!this.message || !this.data.xMailer) {
             return;
diff --git a/package.json b/package.json
index d75e8500..04707fdd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "nodemailer",
-    "version": "4.2.0",
+    "version": "4.3.0",
     "description": "Easy as cake e-mail sending from your Node.js applications",
     "main": "lib/nodemailer.js",
     "scripts": {