Delivery Modes
Every sync rule has a delivery mode that controls how events reach the target calendar. CalendarPipe supports two modes:
- Direct — write events straight into the target calendar via the provider's API.
- Invitation — email events to a chosen address as standard
iCalendar (
.ics) invitations.
You pick the mode when creating a sync rule.
Direct delivery
In Direct mode, CalendarPipe writes events into the target calendar using the provider's API (Google, Microsoft, or Apple/CalDAV). Events appear as native calendar entries — created, updated, and deleted in place as the source changes.
- Available on all plans
- Works with Google, Microsoft, Apple, and hosted calendars
- Requires you to connect the target calendar to CalendarPipe (OAuth for Google/Microsoft, app-password for Apple/CalDAV)
Pick Direct when you control the target calendar and can connect it.
Email invitation delivery
In Invitation mode, CalendarPipe sends each synced event as a
standard email invitation (iTIP/iMIP .ics) to an email address
you specify. The recipient receives a normal meeting invite in their
inbox, clicks Accept, and the event lands on their calendar.
The recipient does not need a CalendarPipe account, an OAuth authorization, or any browser extension or app. Their mail client handles everything — Gmail, Outlook, Apple Mail, Fastmail, and any other client that speaks calendar invitations all work.
- Pro plan only
- One target email per rule
- Works with any source -- a connected Google/Microsoft/Apple calendar, a hosted calendar, or an ICS feed
Why this mode exists
Direct delivery is the simplest option, but it isn't always available. Invitation delivery is built for the cases where it isn't:
- Your company blocks third-party OAuth. Many enterprises lock down Google Workspace or Microsoft 365 so calendars can't be connected to outside apps. Email invitations sidestep this entirely — your IT department already permits inbound calendar invites, because that's how every meeting works.
- You're syncing into someone else's calendar. A partner, client, or teammate whose calendar you can't (and shouldn't) authorize on their behalf still receives invites the same way they'd receive any other meeting.
- You want explicit opt-in per event. Each invitation can be Accepted, Declined, or marked Tentative — handy for optional events or shared schedules.
If your IT policy blocks third-party calendar OAuth, you don't need to give up. Connect any source you can authorize (a personal Google calendar, an Apple calendar, an ICS feed) and use Invitation delivery to send the filtered events to your work email address. The invites arrive like any other meeting and accept straight into your work calendar.
What the recipient sees
A normal meeting invitation in their inbox with the event title, time, location, description, and Accept / Decline / Tentative buttons. Updates and cancellations are delivered as follow-up invitations that update the existing event in place — no duplicate entries.
Limitations
- Pro plan only.
- One target email address per rule.
- The recipient controls whether the event sticks. If they decline or delete an invite, the event is removed from their calendar — but the rule will keep sending future updates to that address.
- Very large recurring series may produce more email volume than Direct delivery, since each occurrence is its own invitation.
Choosing between the two
| Situation | Recommended mode |
|---|---|
| You can connect the target calendar via OAuth | Direct |
| The target is a hosted calendar | Direct |
| Your company blocks calendar OAuth | Invitation (Pro) |
| Syncing into someone else's calendar | Invitation (Pro) |
| You want each event to require explicit accept | Invitation (Pro) |
You can switch a rule's delivery mode later by editing it — but note that changing mode mid-flight will not retroactively rewrite events that have already been delivered the other way.