Update Craft 4: Unfortunately, I will not update this plugin for Craft 4. @Miranj has a plugin with almost the same functionality. To use it with the same twig filters and make the transition more easy, I wrote a small module which you can install. See readme on GitHub.

This plugin provides a Twig Tag that encodes all email addresses in a text field or string by ROT13 ciphering or CSS reversed text direction. A small javascript decodes the addresses again on the frontend.

Usage is very simple: A Twig Tag named obfuscateEmail is provided that can be used in templates:

{{ "Sample Text"|obfuscateEmail }}
{{ textfield|obfuscateEmail }}

The Twig Extension is provided by the Email-Obfuscator by Propaganistas.

Craft Email obfuscator