A catch-all mailbox is one that captures all the email messages sent to invalid addresses. For instance, if your address is email@example.com, but someone mistypes it and sends an email to firstname.lastname@example.org, it will still be received in the catch-all mailbox that you have configured. Only one mailbox per domain can have this feature enabled and in this way you will never miss emails because the other side has an obsolete email address or has made a spelling mistake. The negative aspect of configuring a catch-all mailbox is that you may begin receiving a lot of unsolicited emails, but this problem can be fixed using anti-spam filtering software. It is also crucial to bear in mind that a mailbox with an enabled catch-all feature cannot redirect inbound messages to a third-party address.