Email Hosting Providers

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

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

Web Hosting Providers

SavvisSavvis

Savvis Usage Statistics · Download List of All Websites using Savvis

Enterprise level hosting for media, government, financial, software and retailers. Now owned by CenturyLink.

US hosting

Web Servers

ApacheApache

Apache Usage Statistics · Download List of All Websites using Apache

Apache has been the most popular web server on the Internet since April 1996.