EWS Meeting MCP

EWS Meeting MCP

[npm] [License: MIT] [Node.js >=18] [Python]

[EWS Meeting MCP demo showing a safe Exchange scheduling flow with setup checks, room-aware slot suggestions, preview confirmation, verification, and audit logging]

The MCP server for safely reading Outlook inbox messages, sending self-only reports, and scheduling meetings on on-prem Exchange EWS.

EWS Meeting MCP gives coding assistants and desktop agents a safe, structured way to read Outlook inbox messages and availability, send a report only to the configured mailbox, discover rooms, suggest meeting slots, and create, update, or cancel meetings only after an explicit human confirmation step.

It is built for companies where calendar access is sensitive infrastructure: regulated teams, internal networks, strict security review, legacy Exchange deployments, and organizations that cannot simply hand a cloud agent broad Microsoft 365 permissions. Credentials stay local, meeting writes are previewed before they touch Exchange, self-only report sends require idempotency protection, and every write can be traced through a local audit trail.

npx ews-meeting-mcp

Why This Exists

Many teams still run calendar infrastructure through on-prem Exchange/EWS. General-purpose agents can reason about scheduling, but they should not receive raw passwords, guess attendee addresses, or send calendar invitations without a reviewable checkpoint.

This is not a generic Outlook wrapper or a Microsoft Graph-first calendar connector. It is designed for the stricter enterprise case: local EWS access, room resources, explicit human approval, duplicate-send protection, and audit-friendly meeting lifecycle tools.

This project wraps Exchange calendar operations in a small MCP surface with:

• Room-aware scheduling: finds overlapping attendee availability and filters meeting rooms by Exchange discovery or local policy.
• Human-in-the-loop writes: create, update, and cancel operations require a preview plus a matching confirmation_id.
• Outlook Show As: create or update personal appointments with show_as: "out_of_office" (EWS OOF). Empty attendees and rooms never send invitations; this does not configure email automatic replies.
• Local-first credential handling: reads .env, shell environment, or macOS Keychain without passing passwords through the model.
• Structured recovery: setup failures return machine-readable error codes and user-facing setup commands.
• Auditability: lifecycle previews, confirmed actions, duplicate confirmations, in-progress states, and structured errors are written to a local JSONL audit log.
• Agent-ready instructions: the MCP server exposes tool descriptions and initialization guidance, and the repo includes a companion skill for agents that support skills.

What Agents Can Do

Documentation

• Usage Guide: local setup, Keychain, scheduling policy, smoke checks, CLI examples, MCP config, and npm wrapper details.
• Agent Guide: tool contracts, setup checks, attendee resolution, room selection, preview-confirm flows, audit log, and verification rules.
• Publishing: npm package and GitHub Actions release checklist.

Quick Start

1. Configure EWS

Create a .env file in the working directory or provide equivalent environment variables:

EWS_ENDPOINT=https://mail.company.com/EWS/Exchange.asmx[email protected]EWS_USERNAME='DOMAIN\your_user'EWS_AUTH_TYPE=NTLMEWS_TIMEZONE=Asia/Taipei

Use EWS_AUTH_TYPE=BASIC only if IT confirms Basic auth is enabled and the endpoint is protected by HTTPS.

2. Store the Password

For local development, the generic ACCOUNT_PASSWORD override works, but do not put it in MCP config:

ACCOUNT_PASSWORD='your-password'

On macOS, Keychain is safer than storing the password in .env or MCP client config:

read -rsp "Account password: " ACCOUNT_PASSWORDechosecurity add-generic-password -U -s ews-meeting-mcp-account-password -a 'DOMAIN\your_user' -w "$ACCOUNT_PASSWORD"unset ACCOUNT_PASSWORD

Use the same Keychain service/account pair from any local tool that needs this account password:

ACCOUNT_PASSWORD_KEYCHAIN_SERVICE=ews-meeting-mcp-account-passwordACCOUNT_PASSWORD_KEYCHAIN_ACCOUNT='DOMAIN\your_user'

If ACCOUNT_PASSWORD_KEYCHAIN_ACCOUNT is omitted, EWS_USERNAME is used. ACCOUNT_PASSWORD is only a generic local override; Keychain is preferred.

3. Add the MCP Server

For an npm-installed MCP client:

{  "mcpServers": {    "ews-meeting-mcp": {      "command": "npx",      "args": ["-y", "[email protected]"],      "env": {        "EWS_ENDPOINT": "https://mail.company.com/EWS/Exchange.asmx",        "EWS_EMAIL": "[email protected]",        "EWS_USERNAME": "DOMAIN\\your_user",        "ACCOUNT_PASSWORD_KEYCHAIN_SERVICE": "ews-meeting-mcp-account-password",        "ACCOUNT_PASSWORD_KEYCHAIN_ACCOUNT": "DOMAIN\\your_user",        "EWS_AUTH_TYPE": "NTLM",        "EWS_TIMEZONE": "Asia/Taipei"      }    }  }}

For a local checkout:

{  "mcpServers": {    "ews-meeting-mcp": {      "command": "/path/to/ews-meeting-mcp/.venv/bin/python",      "args": ["-m", "ews_meeting_mcp.mcp_server"],      "cwd": "/path/to/ews-meeting-mcp",      "env": {        "PYTHONPATH": "src"      }    }  }}

Optional: Add an Outlook-Style Signature

Meeting invites append a configured HTML signature by default. Ask the MCP tool for a copyable starter template:

ews_signature_setup_guide

Save the returned sample_html as ews-meeting-signature.html in the MCP working directory, then edit the name, email, title, logo URL, and disclaimer. You can also point to a different file:

EWS_MEETING_SIGNATURE_HTML_PATH=/path/to/ews-meeting-signature.htmlEWS_MEETING_SIGNATURE_ENABLED=true

Use an HTTPS logo URL recipients can access, or replace the <img> source with a base64 data URI. Set EWS_MEETING_SIGNATURE_ENABLED=false to temporarily stop appending the signature.

4. Verify Setup

npx ews-meeting-mcp --cli envnpx ews-meeting-mcp --cli probe

The first command prints the configured endpoint and account without printing the password. The second command validates that the account can connect to EWS.

Agent Workflow

For incoming Outlook mail, search the configured inbox first and then read the selected message:

user asks about company email-> ews_setup_check-> ews_search_emails with the narrowest known filters-> user selects or identifies one message-> ews_read_email with the exact id and optional changekey

These mailbox tools are read-only. They do not mark messages as read, send mail, move messages, or change labels.

For the Thursday Jira weekly-report automation, compose the report from the Jira results and then call the dedicated self-only mail tool through this EWS MCP:

weekly report is ready-> ews_setup_check-> ews_send_email_to_self with subject, body, and a stable idempotency_key-> stop after sent=true; do not use Gmail, to: me, or another mail provider

ews_send_email_to_self takes no recipient, to, cc, or bcc argument. It obtains the only recipient from EWS_EMAIL, sends through Exchange EWS, and appends the configured HTML signature by default. It does not write the email body or recipient address to the audit log. Reuse the same idempotency key for an automation retry; a completed or in-progress key will not call Exchange again.

Scheduling should follow this shape:

user request-> ews_setup_check-> ews_signature_setup_guide, if the user needs help creating the optional HTML signature-> ews_resolve_attendees, if names or aliases are provided-> ews_list_rooms, if a room may be needed-> ews_suggest_slots-> user chooses a slot and room-> ews_create_meeting_preview-> show exact invite details, recurrence if present, and confirmation_id-> user explicitly confirms-> ews_create_meeting_confirmed with confirm=true and the same confirmation_id-> ews_verify_meeting, when item id and changekey are available

Recurring meetings are created by passing a structured recurrence object to both preview and confirmed create calls. For example, "every Monday and Wednesday" uses weekly recurrence:

{  "type": "weekly",  "interval": 1,  "weekdays": ["MO", "WE"],  "range": {    "type": "numbered",    "count": 10  }}

"Every business day until 7/26" means Monday through Friday, without holiday or makeup-day handling:

{  "type": "weekly",  "interval": 1,  "weekdays": ["MO", "TU", "WE", "TH", "FR"],  "range": {    "type": "end_date",    "end_date": "2026-07-26"  }}

If the user asks only for weekdays such as "every Monday and Wednesday" without an end date, occurrence count, or explicit no-end choice, ask for one before previewing.

Existing meeting changes should use exact calendar metadata:

user asks to update or cancel a meeting-> ews_find_calendar_events with the narrowest known time window-> user chooses one exact event, if more than one candidate exists-> ews_update_meeting_preview or ews_cancel_meeting_preview-> show current/proposed details, warnings, and confirmation_id-> user explicitly confirms-> matching confirmed tool with confirm=true and the same confirmation_id

Agents should never infer an event from subject text when multiple candidates are possible.

Safety Model

EWS Meeting MCP is designed around a simple rule: reads may be automated, and every write must have a narrow safety gate. Inbox reads are limited to explicit read-only search and read tools; meeting writes require preview plus explicit confirmation, while the self-only report send requires configured-self enforcement plus idempotency protection.

• Authentication failures are fail-fast: the EWS client uses FailFast, and after one invalid-credential or locked-account response the MCP blocks all later EWS calls in that process. Fix the shared Keychain item and restart the MCP before trying again.
• Confirmed create, update, and cancel tools refuse to run unless confirm=true is passed.
• Confirmed tools require the exact confirmation_id returned by the matching preview.
• Confirmed update and cancel tools also require the exact EWS id and changekey from ews_find_calendar_events or a prior verified result.
• Duplicate confirmed requests return error_code: "duplicate_confirmation" with prior result metadata instead of calling EWS again.
• In-progress confirmations return error_code: "confirmation_in_progress" and should not be blindly retried.
• Preview tools never save, move, delete, or send Exchange notifications.
• ews_send_email_to_self is the only mail-write capability. It is self-only, requires EWS_EMAIL to be configured, and sends a saved draft with EWS CreateItem followed by SendItem; it does not accept an arbitrary recipient.
• Self-only sends require a stable, non-secret idempotency_key. A duplicate or in-progress key is refused before another EWS send. If delivery is uncertain, inspect Sent Items before retrying.
• Self-only send audit entries contain only action/status and non-sensitive delivery/idempotency metadata; they do not contain the configured email address, subject, body, password, or token.
• The local confirmation ledger and audit log store operation metadata, not EWS passwords.

If ews_setup_check returns ready: false, an agent should show the returned user_message or setup_command verbatim and stop. It should not ask for attendee emails or continue scheduling as a workaround.

Scheduling Policy

By default, scheduling tools look for ews-meeting-policy.json in the current working directory. Set EWS_MEETING_POLICY_FILE to point at a different file.

If no policy file exists, built-in defaults are used:

• workday: 10:00 to 18:00
• avoid: 12:00-14:00
• fallback rooms: 2-11, 2-13, 2-14, 3-1, 3-2, 3-4

Live room selection uses Exchange room-list discovery when available, then falls back to configured rooms.

Example policy:

{  "workday_start": "10:00",  "workday_end": "18:00",  "avoid": ["12:00-14:00"],  "rooms": [    {      "alias": "3-1",      "name": "3-1 Meeting Room(12P)",      "email": "[email protected]",      "capacity": 12    }  ]}

Policy rooms are merged with the default fallback rooms by alias. A matching alias overrides the default room, and new aliases are appended.

CLI Usage

The npm wrapper starts the MCP server by default:

npx ews-meeting-mcp

Pass --cli to run the Python CLI through the same package:

npx ews-meeting-mcp --cli envnpx ews-meeting-mcp --cli calendar --days 7

Suggest a 30-minute meeting slot:

npx ews-meeting-mcp --cli suggest \  --attendee [email protected] \  --attendee [email protected] \  --start 2026-06-15T09:00:00+08:00 \  --end 2026-06-19T18:00:00+08:00 \  --duration-minutes 30 \  --limit 5

Preview a meeting invitation without sending anything:

npx ews-meeting-mcp --cli create-meeting \  --attendee [email protected] \  --attendee [email protected] \  --start 2026-06-15T11:00:00+08:00 \  --end 2026-06-15T11:30:00+08:00 \  --subject "Project sync" \  --body "Discuss next steps" \  --location "Webex"

Actually create the meeting and send invitations:

npx ews-meeting-mcp --cli create-meeting \  --attendee [email protected] \  --attendee [email protected] \  --start 2026-06-15T11:00:00+08:00 \  --end 2026-06-15T11:30:00+08:00 \  --subject "Project sync" \  --body "Discuss next steps" \  --location "Webex" \  --confirm

The --confirm flag is intentionally required. Without it, the command prints a dry-run preview and does not call EWS to create the event.

Calendar Show As / 不在辦公室

The create and update preview/confirmed MCP tools accept optional show_as:

Omitting it during creation keeps the existing Busy default; omitting it during updates preserves the stored status. Personal appointments use attendees: [] and rooms: [], and are saved with SendToNone. Existing meetings with attendees or resources retain their invitation behavior. Weekly recurring creation also accepts show_as; recurrence editing capabilities are unchanged.

Call ews_create_meeting_preview with, for example:

{  "subject": "不在辦公室",  "attendees": [],  "rooms": [],  "start": "2026-09-21T09:00:00+08:00",  "end": "2026-09-21T18:00:00+08:00",  "show_as": "out_of_office",  "include_signature": false}

Show the user the start/end, timezone offsets, show_as, and invitation behavior. After explicit confirmation, call ews_create_meeting_confirmed with the same arguments plus confirm: true and the returned confirmation_id. Changing the status after preview invalidates that confirmation. Query/verification tools return the stored show_as and raw legacy_free_busy_status; use ews_verify_meeting to read the server after saving.

See Calendar status usage, MCP update steps, and live verification for update examples and a manual verification checklist. This feature affects the calendar status only, not mail automatic replies.

Local Development

For detailed setup, smoke tests, CLI examples, and MCP client configuration, see the Usage Guide.

The short development loop is:

python3 -m venv .venvsource .venv/bin/activatepip install -r requirements.txtcp .env.example .envnpm test

Run the MCP server from a checkout:

env PYTHONPATH=src python -m ews_meeting_mcp.mcp_server

Companion Skill

The repo includes a companion skill for agents that support skills:

skills/ews-meeting-mcp/SKILL.md

See the Agent Guide for the same workflow in plain Markdown.

Troubleshooting

Operational troubleshooting lives in the Usage Guide. For agent behavior, setup-check handling, and lifecycle safety, see the Agent Guide.

Release

See Publishing.

License

MIT