diff --git a/docs/appenders.md b/docs/appenders.md
index 2a2de16..eceb162 100644
--- a/docs/appenders.md
+++ b/docs/appenders.md
@@ -28,7 +28,6 @@ The following appenders are included with log4js. Some require extra dependencie
 * [logFaces-UDP](logFaces-UDP.md)
 * [logLevelFilter](logLevelFilter.md)
 * [logstashHTTP](logstashHTTP.md)
-* [mailgun](mailgun.md)
 * [multiFile](multiFile.md)
 * [multiprocess](multiprocess.md)
 * [recording](recording.md)
@@ -47,6 +46,7 @@ The following appenders are supported by log4js, but will issue deprecation warn
 * [hipchat](https://github.com/log4js-node/hipchat)
 * [loggly](https://github.com/log4js-node/loggly)
 * [logstashUDP](https://github.com/log4js-node/logstashUDP)
+* [mailgun](https://github.com/log4js-node/mailgun)
 
 For example, if you were previously using the gelf appender (`type: 'gelf'`) then you should add `@log4js-node/gelf` to your dependencies and change the type to `type: '@log4js-node/gelf'`.
 
diff --git a/docs/mailgun.md b/docs/mailgun.md
deleted file mode 100644
index bdf3cf1..0000000
--- a/docs/mailgun.md
+++ /dev/null
@@ -1,30 +0,0 @@
-# Mailgun Appender
-
-This appender uses the [mailgun](https://www.mailgun.com) service to send log messages as emails. It requires the [mailgun-js](https://www.npmjs.com/package/mailgun-js) package to be added to your dependencies.
-
-## Configuration
-
-* `type` - `mailgun`
-* `apiKey` - `string` - your mailgun API key
-* `domain` - `string` - your domain
-* `from` - `string`
-* `to` - `string`
-* `subject` - `string`
-* `layout` - `object` (optional, defaults to basicLayout) - see [layouts](layouts.md)
-
-The body of the email will be the result of applying the layout to the log event. Refer to the mailgun docs for how to obtain your API key.
-
-## Example
-
-```javascript
-log4js.configure({
-  appenders: {
-    type: 'mailgun',
-    apiKey: '123456abc',
-    domain: 'some.company',
-    from: 'logging@some.service',
-    to: 'important.bosses@some.company',
-    subject: 'Error: Developers Need To Be Fired'
-  }
-});
-```
diff --git a/lib/appenders/mailgun.js b/lib/appenders/mailgun.js
index 41ee19d..5fe2c17 100644
--- a/lib/appenders/mailgun.js
+++ b/lib/appenders/mailgun.js
@@ -1,5 +1,9 @@
 'use strict';
 
+/**
+ * This appender has been deprecated.
+ * Updates and bug fixes should be made against https://github.com/log4js-node/mailgun
+ */
 const mailgunFactory = require('mailgun-js');
 
 function mailgunAppender(config, layout) {
@@ -8,7 +12,7 @@ function mailgunAppender(config, layout) {
     domain: config.domain
   });
 
-  return (loggingEvent) => {
+  const appender = (loggingEvent) => {
     const data = {
       from: config.from,
       to: config.to,
@@ -21,6 +25,11 @@ function mailgunAppender(config, layout) {
       if (error !== null) console.error('log4js.mailgunAppender - Error happened', error);
     });
   };
+
+  // trigger a deprecation warning.
+  appender.deprecated = '@logj4s-node/mailgun';
+
+  return appender;
 }
 
 function configure(config, layouts) {
diff --git a/test/tap/mailgunAppender-test.js b/test/tap/mailgunAppender-test.js
index 248bd4a..0b5740b 100644
--- a/test/tap/mailgunAppender-test.js
+++ b/test/tap/mailgunAppender-test.js
@@ -147,8 +147,9 @@ test('log4js mailgunAppender', (batch) => {
     const cons = setup.console;
 
     t.test('should be logged to console', (assert) => {
-      assert.equal(cons.errors.length, 1);
-      assert.equal(cons.errors[0].msg, 'log4js.mailgunAppender - Error happened');
+      assert.equal(cons.errors.length, 2);
+      // errors[0] is the deprecation warning
+      assert.equal(cons.errors[1].msg, 'log4js.mailgunAppender - Error happened');
       assert.end();
     });
     t.end();