The digital rights group Electronic Frontier Foundation (EFF) has cautioned that "Slack stores and is able to read all of your communications, as well as identifying information for everyone in your workspace".[61] While commending the company for "follow[ing] several best practices in standing up for users" concerning government data requests, such as requiring a warrant for content stored on its server, and awarding it four out of five stars in its 2017 "Who has your back" report,[62] the EFF also criticized Slack for "a broad set of exceptions" to its promise to notify users of such requests, and for other privacy shortcomings.[61]