Mailgun - A set of powerful APIs that enable you to send, receive and track email from your app effortlessly whether you use Python, Ruby, PHP, C#, Node.js or Java.
Corrily - Know exactly how to monetize your subscriptions, products, services
Stripe for Gmail - Display customers Stripe information within inbound emails
Shippn - Shop from 25+ countries that don't ship to your country.
Amazon SES - Scale your business email & marketing messages with Amazon Simple Email Service (SES), a cost-effective and reliable cloud email service. Sign up today.
Shippo - Shipping, easy and affordable for everyone. A set of unified APIs and tools that instantly enables you to ship your goods internationally