A catch-all mailbox is one that captures all the messages sent to non-existent email addresses. For example, if your email address is email@example.com, but someone misspells it and sends a message to firstname.lastname@example.org, it will still be received in the catch-all mailbox that you have created. Only one single mailbox per domain name can have this feature activated and thus you will never miss messages because the other party has an obsolete address or has made a spelling error. The negative aspect of using a catch-all mailbox is that you may start receiving lots of spam emails, but this issue can be rectified by using an anti-spam protection solution. It’s also vital to bear in mind that a mailbox with an enabled catch-all functionality cannot redirect inbound emails to a third-party address.