A catch-all email mailbox is one that collects all the messages sent to inactive 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 created. Just one single mailbox per domain can have this feature activated and in this way you will never miss messages because the other side has an obsolete email address or has made a typo. The downside of configuring a catch-all mailbox is that you may start receiving lots of spam messages, but this problem can be fixed by using anti-spam filtering software. It’s also important to know that a mailbox with an enabled catch-all feature cannot redirect incoming emails to a third-party address.