What is the best DIY method to use to prevent air and vapor (moisture) infiltration from exterior walls that have outlets and switches in them? There is already a significant loss of insulation where the electrical box takes up the space. Even worse is when there are easy channels for air carrying vapor to enter and exit these holes in the electrical box. I have heard both good and bad about using caulking or minimal expanding foam on the exterior side of the electrical box. Is there a better solution?
I'm not talking about foaming the inside of the electrical box as I feel that is a very bad idea. Outside the box should not matter as far as I can see. Any better ideas? (Aside from the plastic vapor boxes that are meant to be installed prior to electrical boxes, which don't allow the electrician to install the electrical box without a fight.)