I marked Bruce's response as the Answer. Bounce.io can be turned on and off by domain, but it needs to be done by the system administrator. Therefore, if your email is being hosted for you, contact your provider and ask them to disable it for your particular domain. If they're unsure how to do that, they simply need to log into SmarterMail as the system admin, select and Edit your domain, then uncheck the box next to "bounce.io" on the Features tab.
Derek Curtis
COO
SmarterTools Inc.
www.smartertools.com