A catch-all email mailbox is one that gathers all the email messages sent to invalid addresses. For instance, if your address is firstname.lastname@example.org, but somebody misspells it and sends an email to email@example.com, it will still be received in the catch-all mailbox that you have configured. Only one single mailbox per domain can have this feature activated and in this way you’ll never miss emails because the other side has an out-of-date email address or has made a mistake. The downside of using a catch-all mailbox is that you may start receiving plenty of spam email messages, but this problem can be resolved by using an anti-spam filtering solution. It is also essential to bear in mind that a mailbox with an active catch-all functionality cannot redirect inbound emails to a 3rd-party mailbox.