Good morning @DazFisher!
When using the “Send using your email address” feature you don’t need to edit any PHP scripts. The stack uses your Your Email address from the settings in the stack.
This email address has to match the domain that your site is published to when using the “Send using your email address” feature.
So for example if your site’s URL is
www.mywebsite.com then you’d need to use an email address with that domain, like
email@example.com for it to properly work. Many hosts require this.
If you’ve done this, and are still not getting anything to either your inbox or spam folder, be sure to check that your host has the
mail() function enabled for your PHP installation.