Something that many mass email senders do wrong is saturating their message, whatever it may be, with graphics and flash and overlapping designs. I get tons of emails that look like websites from 2004. I can't figure out why. First of all about 80 percent of the time I'm checking the damn things on gmail for iphone, and the graphics don't load anyway. There was never any chance I was going to read these emails in the first place, but if they won't load quickly ... I'm gen Y, dammit, I'm not gonna give them six seconds of my time. Even on a computer, though, they're usually so damn messy that I rebel. Basic design principle -- draw the eye to one place on the page, don't overwhelm it with too many similar-looking elements. Something has to stand out. But instead, 2004 website style. Mass emails are apparently running about a decade behind.

EDIT: one of the problems is that I have "load images automatically" unchecked in gmail for bandwidth purposes, and I'm never going to go the extra mile and click "load images on this email" for something I barely care about anyway. Marketers and PR guys gotta understand that.

EDIT 2: can I just say that I went looking through my trash folder for examples and found insomniasexx's newsletters, which are the complete opposite of all of this? So fucking readable. Good job.