Another thing about your list. Don’t worry when people unsubscribe — because they will. There are a variety of reasons so don’t take it personal. Maybe they’re just reducing the size of their inbox. Or perhaps they were just interested in your freebie offer. Chance are they were not going to buy from you anyway. Just keep providing quality content and those who join will far exceed those who choose to unsubscribe.
This isn’t an issue of the legitimacy of your business and we certainly don’t have anything personal against your content, however we do have to protect the deliverability of all our customers and the risk associated with these terms is too great for us to take on at this time. Here is a page with more information http://www.mailchimp.com/support/compliance/about-terms-of-use-violation?lptkt=LTK143038471765X
Let your recipients know what you want them to do (sign up for a trial, claim a discount, etc.). An ideal call to action should draw attention, be clear and, of course, be clickable. Design a big button, so it’s easy to click on mobile devices. If your email is long, add another call to action, so your subscribers don’t have to scroll to find it. Make a CTA copy compelling.
I am not signing up for an account so I don't know exactly how the API works, but if I were setting up an iPhone App to work with this, I would use the rails plugin. Rails gives you JSON communication for free (IE no extra work required) http://guides.rubyonrails.org/layouts_and_rendering.html see section 2.2.9. Then use on IOS app use something like: http://code.google.com/p/json-framework/ to interact with that.
Even if you've imported an existing list of contacts, you'll still want an easy way for new fans to join your email list. AWeber's sign up forms provide the perfect solution. Create a simple sign up form for your website, and if you don't have a site, we'll host it for you. Grab the link to your AWeber form and share it on Facebook, Twitter, LinkedIn, or wherever your audience is.