A catch-all mailbox is one that collects all the emails sent to inactive addresses. For example, if your address is email@example.com, but somebody mistypes it and sends a message to firstname.lastname@example.org, it will still be received in the catch-all mailbox that you have created. Just one mailbox per domain can have this feature activated and in this way you will never miss emails because the other party has an out-of-date address or has made a spelling mistake. The negative aspect of setting up a catch-all mailbox is that you may begin receiving lots of unsolicited messages, but this issue can be fixed by using an anti-spam protection solution. It’s also vital to know that a mailbox with an active catch-all functionality cannot redirect inbound emails to a third-party mailbox.