A catch-all mailbox is one that collects all the email messages sent to inactive email addresses. For example, if your email address is firstname.lastname@example.org, but somebody mistypes it and sends a message to email@example.com, it will still be received in the catch-all mailbox that you have configured. Just one single mailbox per domain can have this feature activated and thus you’ll never miss messages because the other party has an out-of-date address or has made a typographical error. The drawback of having a catch-all mailbox is that you may begin receiving plenty of junk emails, but this issue can be rectified using anti-spam protection software. It’s also important to know that a mailbox with an active catch-all functionality cannot redirect inbound messages to a third-party address.