diff --git a/lib/server.js b/lib/server.js
index e0f18d6..a1b6b1d 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -301,6 +301,11 @@ SMTPServerConnection.prototype._onCommand = function(command, payload){
             this._onCommandSTARTTLS();
             break;
 
+        // No operation
+        case "NOOP":
+            this._onCommandNOOP();
+            break;
+
         // Display an error on anything else
         default:
             this.client.send("502 5.5.2 Error: command not recognized");
@@ -607,6 +612,13 @@ SMTPServerConnection.prototype._onCommandEHLO = function(host){
     }).join("\r\n"));
 };
 
+/**
+ * <p>No operation. Just returns OK.</p>
+ */
+SMTPServerConnection.prototype._onCommandNOOP = function(){
+    this.client.send("250 OK");
+}
+
 /**
  * <p>Detect login information from the payload and initiate authentication
  * by emitting <code>'authorizeUser'</code> and waiting for its callback</p>