What's a catch-all email account?
A catch-all email account is an address that is specified to receive all messages that are addressed to an incorrect email address for a domain. For example, you have three email addresses set up for coolexample.com; firstname.lastname@example.org, email@example.com, and firstname.lastname@example.org, you can set up email@example.com as a catch-all email account. Then, any email messages sent to firstname.lastname@example.org (or any other invalid email address), are sent to the catch-all account (email@example.com).
You can set up one catch-all email account per domain name.