Email Hosting Providers

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

SSL Certificates

TERENATERENA

TERENA Usage Statistics · Download List of All Websites using TERENA

The TERENA Certificate Service allowed a variety of digital certificates to be offered to research and education institutions served by participating National Research and Education Networks. Now known as GÉANT's Trusted Certificate Service.

Operating Systems and Servers