Behaviour if Calendar Event Already Exists

When an item is already linked to an existing calendar event, you can choose one of three behaviours:

1. Do nothing
2. Create additional events
3. Update the existing event in some way

1 & 2 are easy, but 3 represents a challenge as you have to consider exactly what to do and the behaviour you require.

The workflow actions allow the following:

Behaviour on event updates

Below is the practical, real-world difference in Outlook calendar behaviour when you:

1. Update the existing event
2. Create a new event & delete the existing one

This matters a lot because Outlook handles identity, attendee user experience, notifications, and tracking differently.

1. Update the existing event

Behaviour for attendees

• Attendees receive an “Updated meeting” email
• Outlook keeps the same meeting ID (iCalUid stays the same).
• Attendees see this as the same meeting, just modified.
• Track status (Accepted / Declined) is preserved.
• Reminders and categorisation are generally preserved for attendees.

Behaviour in the organiser’s calendar

• Same event ID continues to exist.
• Any change you make (time, location, body, attendees, recurrence, etc.) updates the record.
• No duplication.
• Outlook links the update to the existing meeting.

Behaviour in attendees’ calendars

• They keep the same appointment entry.
• Their own modifications (notes, category colours, etc.) may remain, depending on Outlook client rules.

Email notifications

Depending on the type of change:

• Time/location changes → Outlook usually forces a meeting update email.
• Body changes → may or may not send an update (Outlook logic varies).
• Minor metadata (categories, showAs, etc.) → usually no update.

2. Create a new event & delete the existing one

This produces completely different behaviour.

❗ Outlook treats this as TWO SEPARATE EVENTS:

• One cancellation for the old event
• One new meeting invitation for the new event

Behaviour for attendees

Attendees receive:

1. A meeting cancellation
2. A brand-new meeting invite

This is disruptive because:

• Their accepted/declined state resets
• Their notes/categories on the original meeting are lost
• They must accept the new meeting again
• It clutters their inbox with two notifications instead of one

Behaviour in the organiser’s calendar

• You now have a new event ID / iCalUId.
• Any references (like Teams meeting join URL if auto-created) may change.
• Recurrence links break if this was a recurring event.

Behaviour in attendees’ calendars

• The old meeting disappears entirely.
• The new meeting creates a brand-new entry.
• All tracking history is gone.

Email notifications

• Outlook must send a cancellation
• Outlook must send a new meeting invite → You cannot suppress these.

Key Differences Summarised