This document lists all the situations where WordPress sends an email, along with how to filter or disable each email.
This is accurate as of WordPress 4.8, and includes some upcoming changes in WordPress 4.9.
Postal is a complete and fully featured mail server for use by websites & web servers. Think Sendgrid, Mailgun or Postmark but open source and ready for you to run on your own servers. Postal was developed by aTech Media to serve its own mail processing requirements and we have since decided that it should be released as an open source project for the community.
The ancestors of the Internet were kind enough to give us a communication standard which is free, transparent, and standardized. It would be a shame to see the tech communication landscape move further and further into the world of locked gardens and proprietary schemas.