Amazon SNS vs Amazon SES

Pushover

Real-Time Notifications on Multiple Devices

OneSignal

Push Notifications

Twilio

A cloud communication platform, which brings voice, telephony, SMS, and messaging functionality to your app

Pushbullet

An effortless way to send and track transactional emails

Urban Airship

Developer Tools

Mailgun

A Developer-Friendly Email API Service

SparkPost

Email Marketing

SendGrid

Cloud-based email delivery service from Twilio

Mailchimp

Email and marketing platform targeted for small Business

Postmark

Email Marketing