Twinme - Twinme – Private Messenger is a free, secure, instant, and high-definition messaging app that protects your privacy along with giving you full control over each of your relationships and contents.
AWeber - AWeber is an Email marketing software that's easy to use. Send email newsletters & autoresponders and deliver top notch emails.
Textra - Textra is a seriously beautiful, feature rich SMS and MMS app.
Constant Contact - Constant Contact offers email marketing, social media marketing, online survey, event marketing, digital storefronts, and local deals tools.
Material Messaging - Material Messaging is a beautiful communication app that lets you send and receive SMS and MMS messages using the intuitive interface while giving you complete control over every aspect of your messaging experience.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.