One of them came through as plain text, but I assume both of them were sent in HTML?
To start, I would work on your copywriting on the sign-up page and really focus on increasing subscribers. It really is a numbers game. With an expected response rate (in general) of 1/2 to 1 1/2 percent... you need to continuously build on the readership.
The headline describes what they can do, but it doesnt include a compelling
reason to do it. This free headline analysis is really fun and should prove helpful:
http://www.clicknewz.com/695/free-headline-analysis/
Just tweak it a few times and watch the different scores you get and what they mean. There are a couple more great resources here:
http://www.clicknewz.com/681/copywriting-templates/
Oddly enough, you even have to pre-sell FREE stuff! People are busy, and people have a LOT of email, so your copy has to convince them to take that action.