A catch-all mailbox is one that gathers all the emails sent to inactive email addresses. For example, if your email address is email@example.com, but somebody mistypes it and sends an email to firstname.lastname@example.org, it will still be received in the catch-all mailbox that you have configured. Only one single mailbox per domain name can have this feature enabled and in this way you will never miss messages because the other party has an obsolete email address or has made a mistake. The drawback of creating a catch-all mailbox is that you may start receiving plenty of unsolicited messages, but this issue can be rectified by using anti-spam protection software. It’s also crucial to know that a mailbox with an activated catch-all functionality cannot redirect inbound emails to a 3rd-party email address.