Slack uses customer data to train AI models, but claims to have technical controls in place to prevent data leakage across workspaces. Customers can opt out of having their data used to train global models, but this opt-out is only available by email. Slack's AI models are used for features such as channel recommendations, search results, and autocomplete. The company states that it does not use customer data to train generative AI models without affirmative opt-in consent.