MCP server
Connect Claude or ChatGPT to Outlook: Microsoft 365 connector or Kasar
To plug Claude into Outlook, Anthropic offers a Microsoft 365 connector that goes through your Entra directory admin. Kasar opens another door: each person links their Microsoft mailbox to the CRM, then adds Kasar as a connector in Claude or ChatGPT. The assistant reads Outlook mail and calendar, drafts replies, and ties every exchange to the right client.
Facts checked on October 6, 2026
01Built-in route: Claude’s Microsoft 365 connector
Claude’s help centre, checked on 6 October 2026, opens this connector to every Claude plan, from Free to Enterprise. It searches Outlook, SharePoint, OneDrive and Teams. Setup starts on the Microsoft side: an Entra Global Administrator in your organisation authorises the integration before anyone can connect.
Two conditions matter for a small team. The connector needs an Entra tenant tied to a Microsoft business plan, and it turns away personal @outlook.com or @hotmail.com accounts. The write tools, which send email and manage the calendar, also need a fresh admin consent and an opt-in in the Claude organisation settings.
In ChatGPT, OpenAI lists Outlook Email and Outlook Calendar apps. Its developer mode help page adds that OpenAI-built apps are search-only today, with no write actions (checked on 6 October 2026).
02Kasar route: mailbox first, assistant second
- 1
Link your Microsoft account to Kasar
Kasar inbox, email channel, Outlook button: you authorise Kasar in the Microsoft window. Your Outlook calendar comes with the mailbox, no separate connection needed.
- 2
If Microsoft says no: admin consent
Some organisations stop users from approving apps. The directory admin then accepts Kasar once for the whole organisation, with no Kasar account, and each person connects their own mailbox.
- 3
Add Kasar in Claude
Customize, Connectors, “Add custom connector”, then the URL below. On Team and Enterprise, an owner of the Claude organisation declares the connector first, and members connect to it afterwards.
- 4
Authorise, then check
Tick your workspaces on the Kasar authorisation page (OAuth 2.1 with PKCE). Then ask “list my Outlook folders”: the assistant calls crm_mailbox.
A Microsoft account with no Exchange Online mailbox, for instance one without a licence, connects another way: Kasar spots it and offers address and password over IMAP and SMTP. The calendar does not come along in that case.
Adding Kasar in ChatGPT
ChatGPT takes the same URL as a custom MCP app, created under Apps, Create, with OAuth authentication. According to OpenAI’s help centre, write access there is limited to Business, Enterprise and Edu, in beta and on the web, once an admin has enabled developer mode. A Pro account connects the read tools: mailbox, calendar and records can be consulted, while drafts and meetings are created from Claude or Kasar.
03Outlook mail and calendar: the tools involved
Browse the mailbox
- Tool
- crm_mailbox
- Outlook detail
- System folders and folders you created, unread mail, full threads
Draft a reply
- Tool
- crm_draft
- Outlook detail
- A draft in the Outlook Drafts folder, in the original thread
Send
- Tool
- crm_send_message
- Outlook detail
- From the chosen address, after preview and confirmation token
See the week
- Tool
- crm_calendar (list_events)
- Outlook detail
- Live events from the Outlook calendar
Book a meeting
- Tool
- crm_calendar (create_event)
- Outlook detail
- Primary calendar, attendees notified, Teams link on request
Review a past meeting
- Tool
- crm_find_events
- Outlook detail
- Meetings recorded in the CRM, summary and attendees
Bring a contact in
- Tool
- crm_sync_participant
- Outlook detail
- Record created or found, thread linked
04Five prompts for a salesperson on Outlook
- 1
“In my Tenders folder, which emails this week come from existing client companies?”
crm_mailbox reads the Outlook folder you created; the assistant keeps threads whose sender has a record linked to a client company.
- 2
“Find a one-hour slot on Thursday afternoon and offer it to Nadia, with a Teams link.”
crm_calendar reads your calendar, then prepares the event with Nadia invited and a Teams meeting; it is only created once you agree.
- 3
“Draft the reply to Valentin’s requirements document in Outlook, but don’t send it.”
crm_mailbox opens the thread, and crm_draft drops the reply into your Outlook Drafts.
- 4
“What did I promise Pierre at our last meeting?”
crm_find_events finds the meeting linked to Pierre’s record and reads the action items in its summary.
- 5
“Send Hexa’s purchasing team the quote recap from my Outlook address.”
crm_send_message shows the preview, with sender and recipients; the send follows your confirmation.
05What is read, what is written, what waits for you
Reading the mailbox and calendar changes nothing at Microsoft. A draft is written without confirmation, because it never leaves your mailbox. Anything that reaches another person goes through the preview, then the single-use 5-minute token: an email sent, a meeting created, moved or deleted, since attendees get an invitation or an update.
The Kasar calendar tool covers Google and Microsoft calendars, not Exchange calendars connected over IMAP. It writes to the account’s primary calendar. The server caps message sends at 30 per hour per user, and each token is bound to the exact content of its preview.
A sent invitation cannot be taken back: the assistant shows it to you first.
The server-side detail is on the Outlook MCP server page. For Outlook inside Kasar without an assistant, see the Outlook integration page, and to compare CRMs, the MCP server table.
Frequently asked questions
Not always. Each person authorises their own mailbox. The admin only steps in if your directory stops users from approving apps, and then only once for the whole organisation.
Yes, within your plan’s limit. The assistant then reads both mailboxes and, to write or book a meeting, asks which account to use. The preview always shows the sender or calendar it picked.
One per person on Free, two on Pro, five on Max, Gmail and Outlook counted together (see the Pricing page). With several mailboxes, the assistant asks which one to write from.
No, it is added on request. Say “with a Teams link” and the assistant prepares the event with the video meeting, which you approve in the preview.
Sources
Every fact on this page can be checked on the official page below, read on the date shown.
- Claude, aide : Set up the Microsoft 365 connector · read on October 6, 2026
- Claude, aide : Get started with custom connectors using remote MCP · read on October 6, 2026
- OpenAI, aide : Developer mode and MCP apps in ChatGPT · read on October 6, 2026