SPF

   The Sender Policy Framework (SPF) is an email-authentication technique which is used to prevent spammers from sending messages on behalf of your domain. With SPF an organisation can publish authorized mail servers.

G Suite

   formerly Google Apps for Work and Google Apps for Your Domain is a brand of cloud computing, productivity and collaboration tools, software and products developed by Google.

Nginx

   Nginx is a web server which can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache. The software was created by Igor Sysoev and first publicly released in 2004. A company of the same name was founded in 2011 to provide support and Nginx plus paid software.

No Cache Content

   Forces caches to submit the request to the origin server for validation before releasing a cached copy.