Boost your email sales.

Is aweber better than using something like mailchimp?

This probably isn't quite on topic but if you want to increase click-throughs on your email, try adding a web video. Proven to increase click-through rate by up to 96%!!!!!!!

You're basically spamming a large portion of your list as they'll be getting multiple copies. Most of your un-opened segment is going to be people that did get the mail but chose not to open it, or chose not to display images in the mail, which is the default setting in all major webmail and desktop e-mail clients. Your open rate is a measure of how many people loaded a 1x1px tracking image in the mail, nothing more.

If you're concerned about delivery, use a mailing service with a good delivery rate, like MailChimp. Of course, that may not be an option if you're only sending affiliate marketing mails, as they don't take that kind of client -- because it gets reported as spam and the sender blacklisted, over and over, all day every day. Aweber and the few others that cater to IM mailers have worse delivery rates for doing business with that segment, which is why they're 1/10th the size in terms of customers.

You also need to keep your mail from triggering spam filters based on its content. If you have not been taking that into consideration when writing your mails and subject lines, chances are a lot of your messages get delivered but never seen because they're sitting in spam folders. You should use an app like Litmus to estimate how likely you'll trip the most common spam filters with specific messages and learn not to use those words/phrases/etc.