A catch-all mailbox is one that captures all the messages sent to nonexistent email addresses. For example, if your address is firstname.lastname@example.org, but somebody misspells it and sends a message to email@example.com, it will still be received in the catch-all mailbox that you have created. Only one single mailbox per domain can have this feature activated and thus you’ll never miss messages because the other side has an out-of-date email address or has made a mistake. The downside of setting up a catch-all mailbox is that you may start receiving lots of spam emails, but this issue can be solved using an anti-spam filtering solution. It’s also important to bear in mind that a mailbox with an activated catch-all functionality cannot redirect incoming email messages to a third-party email address.