The Plugin Directory at WordPress.org says the following about this plugin: “A lightweight plugin to protect email addresses from email-harvesting robots by encoding them into decimal and hexadecimal entities.”

A lightweight plugin to protect plain email addresses and mailto links from email-harvesting robots by encoding them into decimal and hexadecimal entities. Has effect on the posts, pages, comments, excerpts and text widgets. No UI, no shortcode, no JavaScript — just simple spam protection.