Rule 0: If you want my eyeballs, don't stealth subscribe me to anything. Just because I bought one widget from you does _not_ mean I want to start getting recurring e-mails from you. Violate this, even once, and you've lost my business.
Hmm, this is an interesting business opportunity. I feel the same, but let me prod it further. I suspect the core problem isn't that you're emailing me - it's that you're doing so out of a focus on you, not me. Hear me out: when I go through the email-signup hullabaloo on a website, it's usually because I really want something from there. It's probably a one time thing, and I'll likely forget about your site and bran…
One thing that might help is to keep things VERY brief. If I see a wall of text I instantly go for the delete key. One or two sentences that DON'T look like some canned e-mail I _might_ scan.
But don't waste my time. My time is precious to me, your store (probably) isn't. Imagine if each e-mail you sent to me cost $10 to send. Do you still send that e-mail? If not, don't waste my time.
I also find behavioral targeting very creepy, so that'd be a turn off.