Introduced in version 10.3
Up until now, TYPO3’s system emails were just plain text emails. But not anymore!
TYPO3 v10.3 now supports nice looking template-based HTML and plain-text emails by using the Fluid templating engine. Several emails created by the TYPO3 core use the new format: for example the notification email that can be triggered if a user logs into the backend, or the email that is sent to the appropriate users when an element changes its workspace stage.
Why don’t you trigger a test email in the Install Tool yourself to see how nice an HTML-based email can look?
But this is not all: by overwriting the default paths to the Fluid template files, developers and integrators can implement their own customized email templates. Imagine system-generated notification emails with the brand logo and colors of your agency! How amazing is this?
Documentation