TFS 2013 - Change email content

Question

Is there an option to change the content of the build notification email?

Xslt templates only manipulate with the content but we need to add some new data. Our solution highly depends on a third party application so it would be very helpful to receive the version info of that third party application inside of the build notification email.

So far we have tried to hook onto BuildCompletionNotificationEvent by implementing ISubscriber, but the method ProcessEvent is entered after the notification has already been sent so whatever change is made there is no effect in email notifications.