Outlook

Microsoft is reportedly replacing OpenAI and Anthropic models with its MAI models in Outlook and Excel to cut AI costs.

Who they are

Outlook is Microsoft's email and calendar application, appearing in coverage chiefly as a surface for Microsoft 365 and Copilot features, product migrations, and integrations with workplace software and outside email services.

The recent arc

Coverage peaked around Microsoft's March 2023 Microsoft 365 Copilot announcement, which brought OpenAI's GPT-4 to Outlook alongside Excel, PowerPoint, and Word. In 2024, the focus narrowed from broad generative-AI rollout to task-specific workplace features: Copilot for Finance was introduced for work in Excel and Outlook, and Microsoft added Outlook email-prioritization features while expanding AI tooling elsewhere in its suite.

The latest turn is model infrastructure rather than a new user feature. Bloomberg reported in July 2026 that Microsoft is beginning to replace OpenAI and Anthropic models with its own MAI models in products including Outlook and Excel to reduce AI costs. Between those Microsoft-led developments, Perplexity launched an Email Assistant for Gmail and Outlook, while OpenAI added Outlook among the services accessible through ChatGPT connectors.

The tension

The central tension is Microsoft's effort to make Outlook an AI-enabled work interface while reducing dependence on the external model suppliers that helped power its first Copilot push. Outlook also sits in a contested email ecosystem: Gmail is a frequent comparison and integration target, and Perplexity and OpenAI are using access to inboxes and connected work services to extend their own assistants into the same workflows.

Why it matters

If Microsoft's reported MAI-model shift continues, Outlook could become an important test case for whether Microsoft can lower the cost and deepen control of AI features across its Office applications without weakening the capabilities associated with OpenAI-backed Copilot. At the same time, expanding third-party assistants and connectors may make the value of an email client depend increasingly on which AI systems and work tools it can securely coordinate, not solely on its native inbox features.

Related: Microsoft · Excel · Gmail · OpenAI · Microsoft announces Microsoft 365 Copilot, which will bring OpenAI's G · Microsoft launches Copilot for Finance in public preview, helping user