A catch-all alias is an email account that will catch any email sent to a non-existent email
address under your domain name. Instead of bouncing the email back to the sender, it will
store the email into the account that is assigned as the catch-all account.
Some hosting companies do not support the catch-all alias. The catch-all alias
allows spammers to send unsolicited emails to random email addresses. This creates
stress on the mail servers, slowing down the mail server's normal functionality.