Disable Emails v1.8.1 has just been released. It fixes a fatal exception when an email address was invalid.
Sometimes things can go wrong and emails can be sent to invalid email addresses. The PHPMailer class does a basic check for email addresses at least looking vaguely like email addresses should, and raises and exception when they don’t. WordPress doesn’t crash when this happens, so Disable Emails shouldn’t either! Sorry about that; fixed now.
You can update to the latest version from your WordPress plugin admin page. Here’s the full changelog for Disable Emails.