The MailUp plugin for WordPress (http://wordpress.org/extend/plugins/wp-mailup/) allows you to easily add a newsletter sign-up form to your WorPress website and then run email marketing and SMS campaigns in MailUp.
Give the MailUp plugin a try! Search for it on your WordPress plugin section.
For both Magento Community & Enterprise platforms, the MailUp extension allows you to communicate more effectively with your online customers and: •Identify and segment customers based on specific filters such as geographical area, order amount, purchase history, and more. •Export customer transaction data automatically from your e-commerce store into your MailUp email marketing account. •Create targeted newsletters, triggered, post-purchase emails and smart email marketing campaigns in MailUp.
Check it out on Magento Connect: http://www.magentocommerce.com/magento-connect/mailup.html