diff --git a/lib/mailgun.js b/lib/mailgun.js
index <HASH>..<HASH> 100644
--- a/lib/mailgun.js
+++ b/lib/mailgun.js
@@ -94,6 +94,8 @@ Mailer.send = function (options, callback) {
         mailgunMessage.subject = options.subject || null;
         mailgunMessage.html = options.html || '';
         mailgunMessage.text = options.text || '';
+        mailgunMessage.['recipient-variables'] = options.['recipient-variables'] || '';
+
         if (options.replyTo) {
             mailgunMessage['h:Reply-To'] = options.replyTo;
         }
make recipient-variables availble