Most advertisements (including e-mail adverts) are actually an eye sore to most intended targets, but the fact that e-mail adverts have been abused, it doesn't take away the fact that if done articulately, it remains one of the highest conversion rate adverts, since it can have a one-on-one direct contact touch to it.
Herewith some tips: make sure it has a personal touch to the intended target, and actually provides something a reader will identify with. A good way is to make sure you are using carefully and patiently built lists, as opposed to just grabbing the next list you get your hands across.
There are tricks that you can use to acquire quality e-mail lists through your website, and other means.
Engaging specialist services in 'green' e-mail marketing from the likes of
www.netmarketer.co.za might get you the quality lists faster.
Good luck!