Submitting a blog post to promote your app

I have an app and thought to submit a related article to blogs to get some linkbacks and exposure. Many blogs have a "write for us" where you can submit an article. I thought to write an article and send it to 20 blogs but they all say your blog post needs to be unique. How can you possibly do this? Is there an approach I should be taking or just send the same one to all of them? I just want some exposure baby!