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 example.com: email@example.com, firstname.lastname@example.org, and email@example.com. You can set up firstname.lastname@example.org as a catch-all email account. Then, any email messages sent to email@example.com (or any other invalid email address), are sent to the catch-all account (firstname.lastname@example.org).
You can set up one catch-all email account per domain name.