Creating a hard bounce for old email account?

Creating a hard bounce for old email account?

Hello,

I've had some employees leave and I have deleted their email accounts. Because I have set up a catch-all, I'm now getting all of their emails. Is there a way that I can set up a hard bounce on these addresses to notify that the account no longer exists, or at least an auto response?

I've looked through the Help, but can't find anything.

Thanks
Sarah