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Cal.com is an open-source scheduling tool. Because your Langmail calendars are standard CalDAV collections on mail.langmail.me, Cal.com’s CalDav (Beta) app connects to them directly — no plugin or bridge. Once connected, Cal.com:
  • checks your Langmail calendar for conflicts so it never offers a slot you’re already busy on, and
  • writes each new booking into a Langmail calendar you choose, where your agent, webmail, and every other client immediately see it.
This is the same open-protocol surface the MCP calendar tools use — Cal.com is just another CalDAV client.

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Before you start

Interactive sign-in for Langmail happens in the browser, so Cal.com authenticates with an app password instead of your account password — the same credential mail and calendar clients use. Open webmail, go to Settings → Security, and generate an app password. The secret is shown once, so copy it right away. Use a dedicated app password for Cal.com so you can revoke it independently.

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Connect your Langmail calendar

1

Open the App Store

In Cal.com, go to Settings → Calendars and select Add to open the App Store (or open the CalDav (Beta) app directly).
2

Install CalDav (Beta)

Choose CalDav (Beta) — the generic CalDAV app, not the separate Apple Calendar app, which is hard-wired to iCloud — and select Install. It’s free and available on both Cal.com cloud (app.cal.com) and self-hosted instances.
3

Enter your Langmail details

Fill in the three fields:Cal.com discovers your calendars from the server URL over RFC 6764 (/.well-known/caldav). If it reports that no calendars were found, enter your calendar-home URL instead — https://mail.langmail.me/dav/cal/you%40langmail.me/, replacing you@langmail.me with your own address — the @ percent-encoded as %40.
4

Save

Select Save. Your Langmail calendars appear under Installed Calendars.

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Configure conflict checking and the destination

On the Calendars page, two independent settings control how Cal.com uses the connection:
  • Check for conflicts — toggle each Langmail calendar you want counted as “busy.” Cal.com reads their events and hides any time slot that overlaps one, preventing double-bookings.
  • Add to (destination) — pick the one Langmail calendar Cal.com writes new bookings into. Every meeting booked through Cal.com lands there as a real CalDAV event.
You can check many calendars for conflicts but write bookings to only one.

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How it fits together

Once connected, a booking flows straight into your Langmail mailbox’s calendar:
  1. Someone books a time on your Cal.com page.
  2. Cal.com confirms the slot is free against your Langmail calendar(s), then writes the event into your chosen Langmail calendar over CalDAV.
  3. The event is now a first-class calendar object on the open-protocol surface — your agent, webmail, and any connected calendar client see it at once, and it counts toward conflict checks for future bookings.
Cal.com sends its own booking confirmations and reminders to invitees, so you don’t need Langmail’s iMIP invitations for Cal.com bookings. When you’d rather have your agent schedule and invite attendees directly — recurring series, RSVPs, cancellations — use the calendar workflows instead; both write to the same calendars.
The CalDav app is marked Beta in Cal.com. If a newly booked event doesn’t appear in Langmail, re-check that the destination calendar is set on the Calendars page and that your app password is still valid.

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Next steps

Calendar workflows

Schedule meetings, recurring series, and RSVPs through an agent.

Use a calendar client

Two-way sync with Apple Calendar, Thunderbird, or Android.

Open protocols

The full endpoint map for JMAP, CalDAV, IMAP, and SMTP.