It's about control. With email, I can't control what I receive. If I want to unsubscribe from your newsletter, I'm at the mercy of your site. That sucks. If you want to send me an email because you came up with a message just for me, wonderful! If you want me to ready your form letter that you send to 100,000 people and that I didn't really ask for, fuck you and fuck your conversion rate. Sending me email is a gift; treat it that way.

What's interesting is that newsletters would be better-implemented as RSS/Atom feeds... but nobody ever does that. Why? Because nobody would actually subscribe. Makes you wonder, doesn't it.

(Again, I'm not saying that spam is ineffective, it is effective. But then again, coming up to me and hitting me on the head and taking my wallet would probably get you the money in my wallet faster than creating a business would.)