A catch-all mailbox is one that gathers all the messages sent to non-existent addresses. For example, if your email address is email@example.com, but someone mistypes it and sends an email to firstname.lastname@example.org, 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mailbox per domain can have this feature activated and thus you will never miss messages because the other party has an outdated email address or has made a mistake. The negative aspect of using a catch-all mailbox is that you may begin receiving a lot of junk email messages, but this problem can be solved by using an anti-spam protection solution. It is also crucial to know that a mailbox with an activated catch-all feature cannot redirect inbound emails to a third-party email address.