Guides · Updated 2026-10-29

Why won't my booking tool sync with Outlook or iCloud?

Which Outlook connection does my booking tool use?

“Outlook” can mean three different connections, and each fails in its own way:

If your calendar is in Microsoft 365, the sign-in connection is the usual choice. The Exchange connection is meant for servers you or your IT team run. Calendly also offers an Outlook plug-in for Windows, which its Exchange guide recommends when the Exchange connection uses two-factor or multi-factor sign-in (Calendly help).

A Calendly Community thread titled “Calendly Not Integrating with Outlook – How to Solve” has over 11,000 views. Calendly staff there suggest “ditching the plugin and connecting via O365/Outlook.com instead” when the plug-in causes problems (Calendly Community).

Why does connecting Microsoft 365 say “Approval required”?

Your organization controls which apps can read mailboxes. Calendly’s help page says: “If you see an Approval required message when connecting your Outlook calendar, your organization must approve Calendly before it can access your Microsoft account” (Calendly help).

Microsoft’s own documentation explains why. Admins can restrict or turn off user consent, and Microsoft recommends allowing it “only for applications that have been published by a verified publisher”. When users can’t consent, admins can turn on an admin consent workflow so users can request approval (Microsoft Learn).

Fix: send your IT admin the booking tool’s name and ask them to approve it in the Microsoft Entra admin center, under Enterprise apps > Consent and permissions.

Does the Exchange Web Services retirement break booking tool connections?

It can. Microsoft’s Exchange team announced “a phased, admin controllable disablement plan that starts in October 2026 and concludes with a complete shutdown of EWS in 2027”. Tenants that haven’t set EWS up explicitly have it turned off from 1 October 2026, admins can turn it back on temporarily, and from 1 April 2027 “EWS will be fully and permanently disabled” (Microsoft Tech Community).

The retirement applies only to Microsoft 365 and Exchange Online: “EWS is not being retired on-prem” (same source). So:

• A Microsoft 365 mailbox connected through a tool’s EWS-based Exchange option may stop syncing now.
• An on-premises Exchange server connected over EWS is not affected by this change.
• Microsoft’s guidance is for apps to move to Microsoft Graph. If your booking tool offers both “Exchange” and “Office 365 / Outlook” options, ask the vendor which one avoids EWS before reconnecting.

Can a booking tool connect to Exchange on-premises?

Some can, some can’t:

• Calendly: yes, Exchange 2013, 2016 and 2019 over EWS, but “Calendly can only check your primary Exchange Calendar for conflicts” and “cannot check sub-calendars or shared calendars”. ActiveSync, IMAP and POP connections are not supported (Calendly help).
• Cal.com: has an Exchange app that uses EWS; the listing does not name supported versions (Cal.com).
• SavvyCal: no. “SavvyCal doesn’t connect to other calendar services, or to a CalDAV or Exchange server you host yourself” (SavvyCal docs).
• Microsoft Bookings: no. “Bookings is a cloud-only application. It isn’t supported in a federated or hybrid environment” (Microsoft Learn).

How do I connect a shared mailbox calendar?

A shared mailbox has no password of its own, so you connect it through your own account. Calendly’s steps are: get “Delegate (Can Edit) permissions on the shared mailbox calendar”, add that calendar to your own account in Outlook or Outlook on the web, connect your own Microsoft 365 account in Calendly, then select the shared calendar for conflict checking or new events. Calendly lists only the first 10 calendars Microsoft returns, so you may need to reorder or remove calendars and reconnect (Calendly help). A Calendly Community thread on this question has over 4,000 views (Calendly Community).

Other tools differ. SavvyCal says that on Microsoft 365 “you can only create events on your own main calendar” (SavvyCal docs). Microsoft Bookings creates its own mailbox in Exchange for each Bookings calendar and “uses shared mailboxes in Exchange to store customer, staff, service, and appointment details” (Microsoft Learn).

Why don’t my Outlook events block times on my booking page?

The most common reasons, in Calendly’s documentation:

• The calendar isn’t selected. You choose the calendars to check, and Calendly can check “up to 4 sub-calendars” in Outlook (Calendly help).
• The event status doesn’t count. By default Calendly blocks Outlook events marked Busy, Tentative, Away / Out of Office and Working Elsewhere, but in an Exchange calendar “Working elsewhere” is read as available (Calendly help).
• It’s a subscribed calendar. “Calendly is not able to check subscribed calendars for conflicts”, according to Calendly staff (Calendly Community).

In Microsoft Bookings, check that “Events on Microsoft 365 calendar affect availability” is on for each staff member; staff from outside your tenant can’t share free/busy with Bookings (Microsoft Learn). See how to stop double bookings for the full list of causes.

Why don’t bookings show up in my Outlook calendar?

Booking tools write new events to one calendar, and only one you can edit. Calendly says it “can only add scheduled events to Outlook calendars you have edit access to” and “can’t add scheduled events to calendars you can only view” (Calendly help). Check which calendar is set as the one to add events to.

In Microsoft Bookings, appointments appear through the confirmation email, which includes an .ics file attachment, and “Bookings appointments can only be edited from the Bookings web portal”, not in Outlook (Microsoft Learn).

How do I connect an iCloud calendar to a booking tool?

iCloud uses an app-specific password, not your Apple Account password. Apple says app-specific passwords require “two-factor authentication”, that you can have “up to 25 active app-specific passwords”, and that changing or resetting your main password revokes them all (Apple Support).

1. Turn on two-factor authentication for your Apple Account.
2. At account.apple.com, open Sign-In and Security > App-Specific Passwords and generate one.
3. In the booking tool, enter your Apple Account email and the app-specific password.
4. Select which iCloud calendars to check for conflicts.

Cal.com (docs), SavvyCal (docs) and Doodle (help) all document this method. SavvyCal adds: “Your regular Apple ID password won’t work” (SavvyCal docs).

Which booking tools don’t support iCloud?

• Calendly: “As of August 20, 2024, Calendly no longer supports new connections to iCloud Calendar. Existing connections will continue to be supported” (Calendly help). The Calendly Community thread “iCloud calendar sync no longer possible?” has over 6,700 views (Calendly Community).
• Zoho Bookings: calendar sync covers “Google Calendar, Outlook Calendar, Zoho Calendar, and your Zoho CRM calendar” (Zoho), with no iCloud.
• Setmore: Apple sync is a “1-way sync” that shows Setmore appointments in Apple Calendar; “Mac and iPhone events cannot be exported to your Setmore account” (Setmore support).

Other CalDAV servers are a separate question. SavvyCal connects to iCloud but not to other CalDAV servers (SavvyCal docs). Cal.com’s CalDAV app is in beta and lists Baïkal, Kerio Connect, Nextcloud and Radicale as verified (Cal.com).

How do I fix a calendar that stopped syncing?

Reconnect it. Calendly says disconnects “typically” happen “due to a password change, revoked permissions, or a temporary connection issue”, and that hosts may see “We could not access your [Calendar Name]”. The fix is Settings > Calendar > Re-connect (Calendly help).

• iCloud: after an Apple Account password change, generate a new app-specific password before reconnecting.
• Microsoft 365: if reconnecting asks for approval, your admin has to approve the app again; if the connection uses EWS, see the retirement section above.
• Microsoft Bookings: for “This staff member’s calendar can’t be synced”, Microsoft says to confirm “Events on calendar affect availability” is checked and that the staff member shares their calendar as “Can view when I’m busy” (Microsoft Learn).

Where to compare booking tools

The comparison table lists the calendars each booking tool connects to, free scheduling tools shows what each free plan includes, and pricing compares paid plans.

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