Copilot for Exchange Server on-premises? Doesn't exist. This does.
Microsoft 365 Copilot requires a mailbox in Exchange Online. For self-hosted Exchange Server, Microsoft has so far published only an interest survey - no product. Postgate AI closes that gap today: set up once server-side, usable by all employees, each with their own Exchange permissions - in the familiar chat interface of Claude, ChatGPT or Gemini, on desktop and mobile. An add-in inside Outlook is available as an optional extra.
What Microsoft has announced - and what it hasn't
A survey, not a product
In October 2025, the Microsoft Exchange team published an interest survey on “Copilot for Exchange Server (on-premises)”. Nothing more exists: no product, no roadmap, no confirmed architecture.
Cloud components likely
The survey explicitly asks whether customers would be willing to send Exchange Server data to the cloud. A future Microsoft offering would therefore likely include cloud components - exactly what many on-premises operators want to avoid.
Timeline: years
Even if a product does come: experience shows that years pass between an interest survey and general availability. If you want AI in your mailbox today, you need a solution that runs today.
Microsoft 365 Copilot and Postgate AI compared
The comparison refers to Exchange Server on-premises - where Copilot doesn't reach today.
| Microsoft 365 Copilot | Postgate AI | |
|---|---|---|
| Exchange Server on-premises | Not available - Microsoft 365 Copilot requires a mailbox in Exchange Online. For on-premises there is only the interest survey. | Available today: Exchange Server SE, 2019 and 2016 via EWS - plus Exchange Hybrid and Exchange Online via the Microsoft Graph API. |
| Data flow | Processing in the Microsoft cloud. | Your mailboxes stay in your Exchange. Requests and responses pass through our server in Germany (DPA) - a transparent proxy, no storage, no content logging. If you prefer, even the AI stays entirely on-premises. |
| Permission model | Open for on-premises - the architectures discussed so far rely on central service accounts (service principals). | Every employee accesses with their existing Exchange permissions - delegated, no shared account, no impersonation. |
| AI model | Tied to the Microsoft stack. | Free choice: Claude, ChatGPT, Gemini or local models (e.g. Ollama) - we provide the connection, you choose the AI. |
| Cost | approx. $30 per user per month (Copilot license). | €7.90 per user per month on an annual plan (€8.90 for 3 months, €9.90 monthly) - a fraction of the Copilot license. |
You don't have to decide against Microsoft
Postgate AI is an MCP server - the Model Context Protocol is an open standard through which AI assistants securely access external systems. That means Postgate AI can also be plugged into Microsoft Copilot Studio: your Copilot agent gets the access to on-premises mailboxes that does not exist natively. And should Microsoft deliver later after all, the open standard means you are not tied to any vendor.
Frequently asked questions
Is Copilot coming to Exchange Server on-premises?
Unclear. Since October 2025 there has been an interest survey from Microsoft - no product, no roadmap. The wording of the survey also suggests that a future offering would send Exchange data to the cloud.
Can I combine Postgate AI with Copilot?
Yes. Postgate AI is an MCP server (Model Context Protocol) and can also be plugged into Microsoft Copilot Studio. Your Copilot agent then gets the access to on-premises mailboxes that does not exist natively.
Do our emails leave the company?
Yes, for processing: requests and responses pass through our server in Germany - GDPR-compliant, with a DPA. We operate like a transparent proxy: no storage, no logging of your content. We do not run an AI of our own; you decide which AI model processes your content.
Which Microsoft Exchange versions are supported?
Microsoft Exchange Server Subscription Edition (SE), Exchange 2019 and Exchange 2016 via EWS - including versions whose Microsoft support ended in October 2025. Plus Exchange Hybrid and Exchange Online via the Microsoft Graph API.
AI in your on-premises mailbox - today, not in years
Try Postgate AI free for 7 days with your own Exchange - no credit card, ends automatically.