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. Catch-all aliases can be useful as long as they are monitored and kept clear of unwanted email.
However, due to the nature of email and the amount of spam that is sent every day, a catch-all can become a burden to email systems and to domain administrators. Therefore, it is suggested that they be used sparingly, or not at all if it can be avoided.
Furthermore, it is important to never set an autoresponder on an email account that the catch-all forwards to, as it may result in backscatter, causing additional bandwidth usage and potentially causing your domain to be blacklisted.
