When I worked in e-commerce we ran two extremely different B2C websites. One was purely price based (which sounds like it may be similar to the lighting industry) and if I remember correctly only about 10% of our sales were generated through email.
The other e-commerce site had a very strong brand following, and email was an extremely important way to keep customers engaged and it was directly responsible for over 30% of sales.
So I wouldn't beat yourself up about 6% of sales coming through email, but you may ask yourself if you are targeting your customers correctly. i.e. do you batch and blast every week? Every two weeks? We initially did that for our commodity based site and had horrible response, but when we switched to a model where we targeted users 6 months after their purchase to see if they needed a replacement we saw an increase in success.