A catch-all mailbox is one that collects all the email messages sent to invalid email addresses. For instance, if your address is firstname.lastname@example.org, but somebody mistypes it and sends a message to email@example.com, it will still be received in the catch-all mailbox that you have set up. Just one single mailbox per domain can have this feature enabled and thus you will never miss emails because the other party has an out-of-date email address or has made a typo. The negative aspect of configuring a catch-all mailbox is that you may begin receiving lots of unsolicited email messages, but this issue can be fixed by using an anti-spam protection solution. It’s also essential to keep in mind that a mailbox with an active catch-all feature cannot forward incoming messages to a 3rd-party mailbox.