Microsoft Replaces OpenAI, Anthropic With Own AI in Excel and Outlook

My take: Starting July 7, when you use Copilot in Outlook or Excel for routine tasks, the model processing them may now be Microsoft's own rather than OpenAI's or Anthropic's. The company began that week routing everyday tasks in those two apps to its in-house MAI models, introduced at its Build conference in June.

The reason is economic. Microsoft AI CEO Mustafa Suleiman put it plainly: the goal is to reduce and "ultimately eliminate" the cost of paying its AI partners for every prompt generated by its millions of Microsoft 365 users each day. For now, OpenAI's models remain active for more complex tasks; the routine ones, which represent the bulk of usage, are already going to MAI.

For any company or professional using AI-integrated productivity tools, this is a signal: the model powering your work can change without notice. Building workflow dependencies on a single AI source without monitoring those changes is a real risk. Does your company have a process to evaluate when a vendor switches the model processing your data?