invoke cb

lib/server.js

@@ -359,9 +359,9 @@ WalletService.prototype._notify = function(type, data, opts, cb) {
   this.storage.storeNotification(walletId, notification, function() {
     self.messageBroker.send(notification);
     if (self.emailService) {
-      self.emailService.sendEmail(notification, function() {
-        if (cb) return cb();
-      });
+      self.emailService.sendEmail(notification, cb);
+    } else {
+      return cb();
     }
   });
 };