You may see an error that free/busy information is not available when colleagues try to schedule a meeting with you. This happens because your calendar availability is not being published to your organization’s scheduling system. Free/busy data is a core feature for coordinating meetings in a business environment.
This article explains how free/busy publishing works in a Microsoft 365 or Exchange environment. You will learn the steps to publish your calendar and share your availability with others.
Key Takeaways: Publishing Your Free/Busy Information
- Calendar Properties > Permissions: Sets the default free/busy visibility for all internal users in your organization.
- File > Options > Calendar > Free/Busy Options: Controls how many months of calendar data are published and how often updates are sent.
- Share Calendar > Calendar Properties: Grants detailed viewing permissions to specific individuals inside or outside your organization.
How Free/Busy Publishing Works in Outlook
Free/busy information shows blocks of time in your calendar as Free, Busy, Tentative, or Out of Office. This data is stored on your organization’s Exchange server or in Microsoft 365. When someone in your company schedules a meeting, their Outlook queries this central service to see your availability.
The “not available” error typically means your client is not publishing this data to the service, or the permissions are set too restrictively. You must use an Exchange or Microsoft 365 account for this feature. Internet calendars or personal email accounts do not support publishing free/busy data to an organizational directory.
Prerequisites for Sharing Availability
You need a working connection to your Microsoft Exchange server or Microsoft 365. Your Outlook must be configured in Cached Exchange Mode or Online Mode for an Exchange account. Verify your account type under File > Account Settings. The account type should list “Microsoft Exchange” or “Microsoft 365.”
Steps to Publish Your Default Free/Busy Information
These steps configure the baseline publishing settings and set default visibility for everyone in your organization.
- Open your calendar and access properties
In Outlook, go to the Calendar module. Right-click your primary calendar under “My Calendars” and select Properties from the context menu. - Set the default permission level
In the Properties dialog, click the Permissions tab. In the list labeled “Name,” select Default. In the “Permission Level” dropdown, select Free/Busy time. This publishes basic availability to all internal users. - Configure publishing details
Click the Apply button, then navigate to the File tab on the ribbon. Select Options and choose Calendar from the left sidebar. In the Calendar options window, find the “Free/Busy options” section and click the Free/Busy Options button. - Adjust data range and update frequency
In the Free/Busy Options dialog, ensure Publish my free/busy information is checked. Set “Publish \
How to Share Your Calendar with Specific People
Use this method to give specific colleagues or external guests more detailed access than the default free/busy view.
- Initiate the sharing process
In the Calendar module, click the Share Calendar button on the Home ribbon. Alternatively, right-click your calendar and select Share > Calendar. - Enter the recipient’s address
A new email message opens with the calendar attached. In the To field, enter the email address of the person you want to share with. Use the dropdown menu on the attached calendar icon to select a Detail level, such as “Free/Busy time” or “Full Details.” - Send the sharing invitation
Add any message text and click Send. The recipient will receive an invitation they must accept to see your calendar. - Manage advanced permissions
For precise control, use the Calendar Properties dialog. Right-click your calendar, select Properties, and go to the Permissions tab. Click Add to select a person from the Global Address List, then assign a permission level like “Reviewer” or “Editor.”
Common Mistakes and Limitations to Avoid
Free/Busy Shows Only as “Busy” with No Details
This occurs when the default permission is set to “Free/Busy time” but the sharing invitation was for a higher detail level that the recipient did not accept. The system falls back to the default permission. Ask the recipient to check their inbox for a sharing invitation email and accept it.
External Users Cannot See Your Availability
Free/busy publishing between different organizations requires federation trust. For one-off sharing with an external user, send a formal calendar sharing invitation to their specific email address. They will view your calendar through Outlook on the web.
Updates Are Not Appearing for Others
The free/busy cache on the server updates every 15 minutes by default. Immediate changes will not be visible to others until the next publish cycle. You can force a manual update by closing and reopening Outlook.
Calendar Sharing Permission Levels Compared
| Item | Free/Busy Time | Full Details |
|---|---|---|
| Can see time as Free, Busy, Tentative, OOF | Yes | Yes |
| Can see meeting subject and location | No | Yes |
| Can see full meeting details and notes | No | Yes |
| Can create and edit appointments | No | Only with “Editor” role |
| Typical use case | Default for all internal colleagues | Sharing with an assistant or close team |
You can now publish your free/busy information and share your calendar with specific people. This resolves the common error where your availability shows as not available. For more control, explore the delegate permissions feature under File > Account Settings > Delegate Access. An advanced tip is to use the Outlook on the web portal to share your calendar with someone outside your organization who does not use Outlook.