This interface allows you to set up a default address (a catch-all address) that receives any mail for an invalid email address for the domain. You can also define how the default address handles incoming messages.
The default address may receive messages for your existing email addresses if they contain typos or other issues. For example, if your email address is email@example.com but a sender uses firstname.lastname@example.org, the default address will receive it. Check your domains’ default addresses often for missing messages.