postale.io is described as 'Free domain email service. Simple, safe, fast, 7/7 free support, and all the essential features a mail service should have'. There are more than 10 alternatives to postale.io for a variety of platforms, including the Web, Android, iPhone, iPad and Android Tablet. The best alternative is ProtonMail, which is both free and Open Source. Other great apps like postale.io are Gmail (Free), Tutanota (Freemium, Open Source), Outlook.com (Freemium) and Zoho Mail (Freemium).