Workplace by FacebookWorkplace by Facebook

Workplace by Facebook Usage Statistics · Download List of All Websites using Workplace by Facebook

Group discussion, a personalised News Feed, and voice and video calling from Facebook.

Email Hosting Providers

MailgunMailgun

Mailgun Usage Statistics · Download List of All Websites using Mailgun

Mailgun is a set of APIs that allow you to send, receive, track and store email effortlessly.

Transactional Email

SPFSPF

SPF Usage Statistics · Download List of All Websites using SPF

The Sender Policy Framework is an open standard specifying a technical method to prevent sender address forgery.

Standard

Google Apps for BusinessGoogle Apps for Business

Google Apps for Business Usage Statistics · Download List of All Websites using Google Apps for Business

Web-based email, calendar, and documents for teams. Renamed to Google Apps for Work, but now known as G Suite From Google Cloud.

Business Email Hosting

DMARCDMARC

DMARC Usage Statistics · Download List of All Websites using DMARC

A technical specification created by a group of organizations that want to help reduce the potential for email-based abuse

Standard

Operating Systems and Servers