Overview
You can use a shared mailbox calendar with Calendly, but you must first add the shared calendar to your own Microsoft 365 account so it appears in your calendar list. Calendly can only see calendars that are added to the connected Microsoft 365 account; opening the mailbox via “Open another mailbox” does not expose its calendar to Calendly.
Step-by-Step Instructions
- Add the shared calendar to your Microsoft 365 account: In Outlook or Outlook on the web, add the shared mailbox calendar so it appears alongside your calendars in your account. (Ensure you have Delegate/Can Edit permissions)
- Connect Microsoft 365 to Calendly: In Calendly, go to your calendar connection settings and connect your Microsoft 365 account using your individual credentials.
- Select the shared calendar in Calendly: Once connected, choose the newly added shared calendar as an active calendar for conflicts and/or as the destination calendar for events, as needed.
- Verify availability and test: Create a test event type and preview availability to confirm Calendly can read busy times from the shared calendar. Book a test event and confirm it lands on the shared calendar you selected.
Key Notes & Limitations
- Calendly only detects calendars that are added to the connected Microsoft 365 user’s account. Calendars accessed only via “Open another mailbox” will not appear for selection in Calendly.
- Each user who wants to use the shared calendar in Calendly must add that shared calendar to their own Microsoft 365 account first.
- You must authenticate to Calendly with your own Microsoft 365 credentials; you cannot log in directly as the shared mailbox.
- You must have Delegate permissions for the shared calendar in order to view it in Calendly
Frequently Asked Questions
Q: Why don’t I see the shared mailbox calendar as an option in Calendly after connecting Microsoft 365?
A: It hasn’t been added to your account yet. Add the shared mailbox calendar to your Microsoft 365 account so it shows in your calendar list; then it will appear in Calendly to select.
Q: Can multiple team members connect the same shared calendar?
A: Yes. Each person should add the shared calendar to their Microsoft 365 account. After that, they can select it in Calendly for conflict checks or as a destination calendar according to their permissions.
Q: Do I need to remove “Open another mailbox” access?
A: No, but relying only on “Open another mailbox” won’t make the calendar selectable in Calendly. You must add the shared calendar to your account for Calendly to recognize it.
Q: What happens if I have more than 10 shared/subcalendars?
A: Calendly only shows the first 10 Microsoft returns. Unsubscribe from unused calendars or reorder them in Outlook on the web, then disconnect/reconnect to refresh.
Q: Will reordering calendars in Outlook change what Calendly shows?
A: In many orgs, yes. Reorder in Outlook on the web, then disconnect & reconnect in Calendly to refresh.
Links & Resources
