Organizations with an Exchange Hybrid configuration often rely on seamless collaboration between Exchange Online and Exchange On-Premises users. However, calendar availability issues can arise, preventing Exchange Online users from viewing Free/Busy (F/B) information for on-premises calendars. This guide explains why this issue occurs and provides step-by-step solutions to resolve it.
In a hybrid Exchange environment, calendar availability information is shared through the Availability Service using Free/Busy lookup. When Exchange Online users cannot access calendar details of on-premises users, it often points to a misconfiguration in:
Addressing these factors ensures a seamless hybrid environment where users can collaborate effectively.
Check Organization Relationship settings to confirm sharing policies:
Get-OrganizationRelationship | Format-List
Key parameters to verify:
https://mail.contoso.com/EWS/Exchange.asmx
.True
.Update the settings if incorrect:
Set-OrganizationRelationship -Identity “OnPremisesRelationship” -TargetSharingEpr “https://mail.contoso.com/EWS/Exchange.asmx”
Confirm the Federation Trust configuration:
Get-FederationTrust | Format-List
If missing or invalid, recreate the Federation Trust using the Exchange Admin Center (EAC) or PowerShell.
Ensure OAuth authentication is enabled for secure connections:
Get-IntraOrganizationConnector | Format-List
Recreate or update the connector if required:
New-IntraOrganizationConnector -Name “HybridConnector” -TargetAddressDomains contoso.com -DiscoveryEndpoint “https://outlook.office365.com/autodiscover/autodiscover.svc”
Use the Microsoft Remote Connectivity Analyzer at testconnectivity.microsoft.com to verify Autodiscover functionality.
Also, run the following PowerShell command:
Test-OutlookWebServices -Identity user@domain.com
If errors occur:
Set-ClientAccessServer -Identity CAS01 -AutoDiscoverServiceInternalUri https://mail.contoso.com/autodiscover/autodiscover.xml
Verify Free/Busy lookup between environments:
Test-FederationTrust
Test-OrganizationRelationship -Identity “OnPremisesRelationship”
Review results and resolve any reported errors.
Ensure the following rules allow required traffic:
Test-WebServicesConnectivity -MailboxCredential (Get-Credential)
Resolve firewall or proxy blocks based on results.
Rerun the HCW to repair hybrid configurations:
Configuring and troubleshooting hybrid Exchange environments can be complex, particularly when integrating calendar availability. Medha Cloud simplifies this process by providing:
Calendar availability between Exchange Online and On-Premises is critical for seamless collaboration. While hybrid configurations introduce complexities, following this step-by-step troubleshooting guide can resolve most issues.
For businesses facing persistent Exchange Hybrid challenges, Medha Cloud offers expert migration, configuration, and troubleshooting services to streamline Exchange environments.
For professional assistance, Contact Medha Cloud—your trusted Microsoft Certified Partner. From setup to ongoing support, we make Exchange Hybrid environments work effortlessly for your business.
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