diff --git a/booking.module b/booking.module
index 7780aa0..15b3e27 100644
--- a/booking.module
+++ b/booking.module
@@ -73,6 +73,8 @@ module_load_include('inc', 'booking', 'booking.rooms_admin');
 module_load_include('inc', 'booking', 'booking.stripe');
 // Load the include for miscellaneous functions
 module_load_include('inc', 'booking', 'booking.misc');
+// Load the include for the extended mail system
+module_load_include('inc', 'booking', 'booking.MailSystemInferface');
 
 function booking_init() {
 	date_default_timezone_set(date_default_timezone(FALSE));