A simple proxy for your email address which creates aliases which can be easily disconnected to prevent unwanted email spam and protect your privacy. It consists of a web app and a cross-browser extension.
Apple introduced a similar concept with Sign in with Apple at WWDC 2019, but forwardmail was before them!
Discontinued, but still used by a few people.
When you create an alias, it generates a random string uses the Gandi.net API to create a forwarding alias to your actual email address using that string. When you disconnect an alias, it deletes the alias from Gandi.net.