@SimonWoods There should be a checkbox, Obfuscate email address, in the settings. If you can't see it, you're probably not on the latest version (1.2.0).
I won't go into the implementation details here, as that kind of defeats the purpose of trying to obfuscate the email. I don't want to help the script kiddies too much. If they absolutely want to scrape email addresses off the lovely people here, at least they have to work for it and figure out the scheme by themselves.
It's JavaScript-based, though, so if that's a no-no for anyone, they should disable the feature and the plug-in will revert to the previous version's functionality.