Boxbe is a free service that purports to prioritize and screen spam in personal email. Users can select which email they want to receive, and which email goes to spam. It presents a challenge to the sender that requires a human response. Boxbe has been criticized for spamming users' contacts without their permission. Boxbe starts with the user allowing Boxbe access to all of the users Email contacts. Boxbe then gives priority to contacts that users allow. Integration within Gmail (including Google Apps), AOL, Yahoo! Mail and their affiliates lets Boxbe stay up to date so it can screen email.