A catch-all email mailbox is one that collects all the email messages sent to nonexistent addresses. For example, if your email address is info@domain.com, but someone miswrites it and sends a message to inof@domain.com, it will still be received in the catch-all mailbox that you have configured. Only one mailbox per domain can have this feature activated and in this way you will never miss emails because the other party has an obsolete address or has made a spelling error. The downside of setting up a catch-all mailbox is that you may start receiving a lot of spam messages, but this issue can be solved using an anti-spam protection solution. It is also vital to bear in mind that a mailbox with an enabled catch-all functionality cannot redirect incoming messages to a 3rd-party mailbox.