A catch-all mailbox is one that collects all the emails sent to invalid addresses. For example, if your address is email@example.com, but someone misspells it and sends an email message 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mailbox per domain can have this feature enabled and thus you’ll never miss emails because the other party has an out-of-date email address or has made a typographical error. The downside of having a catch-all mailbox is that you may begin receiving a lot of unsolicited messages, but this issue can be resolved using anti-spam filtering software. It’s also essential to know that a mailbox with an active catch-all functionality cannot forward inbound email messages to a 3rd-party mailbox.