Postie Gallery Settings

I have used Postie with much success and have now added the Lightbox Plus plugin.
What I would like is for any attached images sent via e-mail to immediately be displayed using the Lightbox feature. I currently have to go and edit the image via the dashboard and wondered if this was a simple code edit? I note that there is a facility to add a custom image template but have no idea how to edit this or where to add it?
Any help what be gratefully received.

http://wordpress.org/extend/plugins/postie/