The ZeroBounce integration is native in our app, and is completely up to you if you'd like to use it or not. 😀
That said, if you are using it, there are some options in your settings to determine what validation codes you'd like emails to be sent to. There is always the risk with any returned code (less likely with the valid code), that an email may bounce, even if it comes back as a catch-all.
For Example: If your ZeroBounce settings are set to send to valid, catch-all, and unknown validations. Catch-all emails can be safe, but depending on the email there is a 2-40% chance that it could bounce. There are mechanisms to score or grade the catch-all emails, one of which we will be adding to the system over a period of time, but if you do not want to run that risk and only want to send to valid email addresses, you may remove the catch-all and unknown from your settings.