Selecting Default Address will allow you to set what action the mail server will take when mail is sent to an e‑mail address you have not set up a real e‑mail account or e‑mail forwarding for.

By default, cPanel is usually set to forward all mail to the default e‑mail address (though your web host can change this default). Alternatively, you can set e‑mail to non‑existent addresses to be instantly discarded with no warning (set the action to :blackhole:) or have the e‑mail bounced back to the sender with a message noting that the e‑mail was undeliverable (set the action to :fail: no such address here). As a general rule, it is a good idea to leave the default e‑mail address set to :fail:.