BuiltWith for GMail
⏰ Old Post
This post is over 6 years old - it might be slightly outdated and consigned to the history books.
https://gsuite.google.com/marketplace/app/builtwith/422986805793
This new Add-on lists all of the technologies that are in use on the domain of the email that you receive, allowing you to quickly vet inbound leads and it's totally free to install!
