A catch-all email mailbox is one that gathers all the emails sent to non-existent addresses. For instance, if your 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 created. Just one single mailbox per domain can have this feature activated and in this way you will never miss emails because the other party has an obsolete address or has made a typo. The drawback of having a catch-all mailbox is that you may start receiving lots of spam, but this issue can be rectified using an anti-spam protection solution. It’s also crucial to keep in mind that a mailbox with an activated catch-all functionality cannot forward inbound email messages to a third-party email address.