Demystifying Hybrid Free/Busy: what are the moving parts?
Hybrid Free/Busy is one of those things that many people do not fully understand. If everything works well, the complexity is hidden from view and people working in various parts of organization can seamlessly work together. But if things go wrong… you will appreciate deeper understanding of what makes it work. This is why we wanted to create the blog post series on the subject. In this article, we will discuss how Free/Busy works in an Exchange Hybrid configuration. In next blog post, you will learn what we (Microsoft Support) see as the most common problems along with how we go about diagnosing those (often) complex issues. Hope you like reading, because there is a lot to cover! So, what is Free/Busy? Free/Busy is a feature that allows you to see when others are free (their calendar shows availability), busy (their calendar shows them as busy), or even Out of Office, or Something Else (tentative or working away) so that you can find an appropriate time for your meetings. Calling it all “Free/Busy/OOF/Something-Else” didn’t sound so cool to marketing hence “Free/Busy”. In a Hybrid deployment, we usually have some mailboxes in Exchange On-Premises and some mailboxes in Exchange Online (users are in different premises) and this has to work there too. One of the most important parts in Hybrid Configurations is the Federation Trust and many features, including Free/Busy can rely upon this. A quick overview of a hybrid deployment with a focus on Federation Trust components In Contoso – On-Premises side we have on-premises Exchange Servers and mailboxes. We also have a federation trust with the Microsoft Federated Gateway (MFG) - now called Azure Authentication System. A Federation trust is not set by default for Exchange On-Premises organizations and we can either create it manually or run the Hybrid Configuration Wizard (HCW) which will do this for us. If you don’t have already a federation trust established on-premises (usually for purposes to share F/B with another on-premises organization) and you plan for a Hybrid deployment, then we strongly recommend you run HCW to automatically create the Federation Trust. In Contoso – Cloud Side there are Office 365 Exchange Online servers, your Office 365 tenant and mailboxes migrated from on-premises. A Federation trust with the MFG is automatically created for cloud-only-based Exchange organizations whom do not have a Hybrid relationship to an on-premises organization. If you run Get-FederationTrust cmdlet in Exchange Online PowerShell (see here how to connect to Exchange Online PowerShell) you would see two trusts: “WindowsLiveId” (Consumer Instance of Microsoft Federation Gateway) and “MicrosoftOnline” (Business Instance of Microsoft Federation Gateway) . Note: As a troubleshooting tip, you might want to make sure the Application Identifier is “260563” and the Application Uri is “outlook.com” for both; in case you have a different App ID (292841) and a different App URI (outlook.live.com) for a Cloud trust, this means your tenant has an old reference pointing to MFG and most probably Free/Busy from on-premises to cloud would fail with a quite generic 401 Unauthorized error. If you were to find yourself in a such situation, please open a support case with Microsoft to get it resolved. About Free/Busy lookup directionality To guide you to the correct troubleshooting steps we first need to determine what direction Free/Busy queries are failing in. Understanding how Free/Busy works in general and the direction that lookups are failing can greatly simplify the troubleshooting steps. Simply said, there are 2 possible Free/Busy directions (referring to our example above): When Joe looks up Jane’s Free/Busy, the Free/Busy direction is On-premises to Cloud. When Jane looks up Joe’s Free/Busy, the Free/Busy direction is Cloud to On-Premises Now that you are familiar with the Free/Busy directions, we should take a moment to discuss how it all works. Let me set the stage for the below diagram: joe@contoso.com has his mailbox in Exchange on-premises and jane@contoso.com has been moved to Exchange Online. In Exchange on-premises, joe@contoso.com is a Mailbox User. Because Directory Synchronization is a requirement for Hybrid Deployments, joe@contoso.com (mailbox) is synced to the cloud and represented as a Mail Enabled User (MEU) object in Cloud with Target Address (TA) of joe@contoso.com. jane@contoso.com was once a Mailbox User in Exchange on-premises. Her mailbox was then migrated to Exchange Online. Jane now has a Mailbox User in Exchange Online and is represented as a Remote Mailbox (RM) object in Exchange On-Premises. Jane has a Primary SMTP address (SMTP: jane@contoso.com) and a secondary smtp address (smtp: jane@contoso.mail.onmicrosoft.com). Notice how we refer to a primary email address (SMTP) and to a secondary email address (smtp). According to TechNet, the difference between primary and secondary addresses is that the primary address serves as the return e-mail address. When mail is received from a recipient, the primary address determines which address the mail appears to have come from. Recipients can receive mail sent to any of the addresses associated with them (primary or secondary). The Target Address (TA) of the on-premises Remote Mailbox object is represented as jane@tenant.mail.onmicrosoft.com (secondary smtp) and this is crucial for Autodiscover and email routing from on-premises to cloud. A successful Autodiscover query is important in the Free/Busy process as it provides us with the Availability Service URL of the user which is the External EWS URL of an Exchange Organization. This TechNet article gives us more information on this <domain>.mail.onmicrosoft.com secondary email address: The wizard (HCW) adds an accepted domain to the on-premises organization for hybrid mail flow and Autodiscover requests for the cloud organization. This domain, referred to as the coexistence domain, is added as a secondary proxy domain (contoso.mail.onmicrosoft.com) to any email address policies which have PrimarySmtpAddress templates for domains selected in the Hybrid Configuration wizard(contoso.com). By default, this domain is <domain>.mail.onmicrosoft.com. Table below illustrates the hybrid user objects discussed above as well as how to look them up. On-premises commands = Exchange Management Shell Cloud commands = Exchange Online PowerShell Typical Hybrid user objects configuration On-premises commands On-premises objects Corresponding cloud objects Cloud commands ON-PREM MAILBOX USER MAIL ENABLED USER IN CLOUD Get-mailbox Joe@contoso.com | FT PrimarySMTPaddress On-premises mailbox user with SMTP: Joe@contoso.com Cloud mail enabled user with SMTP: Joe@contoso.com Get-MailUser Joe@contoso.com | FT PrimarySMTPAddress (Get-mailbox Joe@contoso.com). EmailAddresses On-premises mailbox user has a secondary smtp address of @contoso.mail. onmicrosoft.com configured by HCW (Email Address Policies) Cloud mail enabled user has this secondary smtp Joe@contoso.mail. onmicrosoft.com (Get-mailuser Joe@contoso.com). EmailAddresses (Get-mailbox Joe@contoso.com). EmailAddresses On-premises mailbox user has a secondary smtp Joe@contoso.mail. onmicrosoft.com Cloud mail enabled user has an ExternalEmailAddress Joe@contoso.com Get-MailUser Joe@contoso.com |FT ExternalEmailAddress REMOTE MAILBOX ON-PREM MAILBOX USER IN CLOUD Get-RemoteMailbox Jane@contoso.com |FT primarySMTPaddress Remote mailbox SMTP: Jane@contoso.com Mailbox User SMTP: Jane@contoso.com Get-Mailbox Jane@contoso.com |FT PrimarySMTPAddress Get-RemoteMailbox Jane@contoso.com | FT RemoteRoutingAddress Remote mailbox TargetAddress: Jane@contoso.mail. onmicrosoft.com Mailbox User smtp: Jane@contoso.mail. onmicrosoft.com (Get-Mailbox Jane@contoso.com). EmailAddresses Now that we understand user objects and their relevant properties, we should come back to Free/Busy directions. Between the on-premises organization and cloud organization there are bidirectional Organization Relationships and/or bidirectional Intra Organization Connectors (for Exchange 2013 or later) that are created during Hybrid Configuration. The source of these Relationships / Connectors plays an important role in the F/B directionality. The Free/Busy directions are: Direction On-premises to Cloud You are logged in to Outlook on the Web or Outlook on Windows as an on-premises user (joe@contoso.com), you’re your mailbox hosted on your on-premises Exchange server. As an on-premises user you wish to have a meeting with the cloud user (jane@contoso.com) but will first have to check their availability for the meeting. Let’s walk through the process: 1. Joe creates a meeting request and adds Jane as an attendee. 2. The on-premises Exchange server in Contoso determines (usually based on Target Address of the mail-enabled user) that Jane is not a local mailbox and has a different domain name of contoso.mail.onmicrosoft.com set as the Target Address. 3. The Availability Service on the on-premises Exchange server (Client Access Server if Ex2010 or Mailbox Server if 2013/2016) in Contoso then checks to see if there is a path to query Jane’s Free/Busy information for Contoso’s cloud side. First, we check if we have an Intra-Organization Connector (1) with the domain name of contoso.mail.onmicrosoft.com (assuming the Exchange server is version 2013 or later). If an IOC does not exist, then we look to see if an Organization Relationship (2) is configured by looking for the domain name of contoso.mail.onmicrosoft.com in the list of any existing Organization Relationships. If neither an IOC nor an Organization Relationship for the domain contoso.mail.onmicrosoft.com exists, then we look for the domain name contoso.mail.onmicrosoft.com as an Availability Address Space (3). 4. Assuming we would have an Exchange 2010-only environment in the on-premises and we’ve ran HCW successfully, we should expect to see both an Organization Relationship as well as a Federation Trust which combined is the second option from step #3. The Target ApplicationURI in the Contoso on-premises Organization Relationship is set to outlook.com, which is an identifier for the Contoso Cloud organization trust in the Azure Authentication System. A request is then made to the Azure Authentication System for a delegation token that will be accepted by Contoso Cloud Organization. 5. Once the delegation token is received back from the Azure Authentication System, the Exchange server in Contoso on-premises sends an Autodiscover request to Exchange Online, and upon a successful Autodiscover response will send an EWS request to Exchange Online for Jane’s availability information. 6. The Exchange Online server validates the token provided by the Azure Authentication System and once confirmed, returns the requested Free/Busy data for Jane’s mailbox. Here is a flowchart which illustrates the Free/Busy lookup process: Direction Cloud to on-premises You are logged in to Outlook on the Web or Outlook on Windows as a cloud user (jane@contoso.com), whose mailbox is in Exchange Online. Jane wants to have a meeting with an on-premises user (joe@contoso.com), but must first check their availability for the meeting. 1. Jane creates a meeting request and adds Joe as an attendee 2. The Exchange Online servers in Contoso-cloud side organization determine (usually based on target address of a mail-enabled user) that Joe is not a local mailbox and has a domain name of contoso.com set as the target address. 3. The Availability Service on Exchange Online servers checks to see if there is a path for it to find the Free/Busy information for Contoso on-premises side organization. First, we check if we have an Intra-Organization Connector (1) with the domain name of contoso.com (assuming the Exchange server is 2013 or later on-premises). If an IOC does not exist, then we look to see if an Organization Relationship (2) is configured by looking for the domain name of contoso.com in the list of any existing Organization Relationships. If neither an IOC nor an Organization Relationship for the domain contoso.com exists, then we then look for the domain name contoso.com as an Availability Address Space (3). 4. Assuming we would have an Exchange 2010-only environment in the on-premises and we’ve ran HCW successfully, we should expect to see both an Organization Relationship as well as a Federation Trust which combined is the second option from step #3. The Target ApplicationURI in the Contoso Cloud Organization Relationship is set to FYDIBOHF25SPDLT.contoso.com, which is an identifier for the Contoso on-premises organization trust in the Azure Authentication System. A request is then made to the Azure Authentication System for a delegation token which will be accepted by Contoso on-premises organization. 5. Once the delegation token is received back from the Azure Authentication System, the Exchange Online server in Contoso cloud sends an Autodiscover request to the on-premises Exchange Servers and upon receipt of a successful Autodiscover response it will then send an EWS request for Joe’s availability. 6. The Contoso on-premises Exchange server validates the token provided by the Azure Authentication System and once confirmed, returns the requested Free/Busy data for Joe’s mailbox. Hybrid Free/Busy lookup order To summarize, the following order would be used when processing for Free/Busy lookups from cloud to on-premises: Look for IntraOrganizationConnector (OAUTH) If there is no IntraOrganizationConnector or if it is disabled, then look for Organization Relationship (DAUTH) If neither of these are found or they’re disabled, then look for Availability Address Space. Availability Address Space is normally only used for Lotus Notes organizations. If Free/Busy lookup is getting all the way down to using the final Availability Address Space option for cloud to on-premises lookups in a hybrid deployment, then this would suggest there are configuration issues which must be repaired. The order for Free/Busy lookups from on-premises to cloud is almost the same with some exceptions: If we have Exchange 2007 servers in coexistence with Exchange 2010/2013, we use Availability Address Space from Exchange 2007 to Exchange 2010/2013 and then Exchange 2010/2013 will use Org Relationship (Ex2010) or IntraOrganization Connector (Ex2013) to Cloud. If we have Exchange 2010 with Exchange 2013/2016 and OAuth is enabled, Exchange 2010 will use Availability Address Space to Exchange 2013/2016 and then 2013/2016 will use the IntraOrganization Connector to Cloud. If we have Exchange 2010 with Exchange 2013/2016 and OAuth is not enabled, Exchange 2010 will not send the request to the Exchange 2013/2016. Instead Exchange 2010 will use Organization Relationship to Cloud for Free/Busy. Exchange 2013 Cu5+ and Exchange 2016 organizations without coexisting with legacy Exchange servers will use by default IntraOrganization Connectors from On-Premises to Cloud (normal process) This table summarizes which components (Get-IntraorganizationConnector / Get-OrganizationRelationship / Get-AvailabilityAddressSpace) are present (YES) or not (NO) in the Exchange Organization depending on the Exchange Server versions on-premises in a Hybrid deployment. Free/Busy component matrix Exchange Hybrid Environment Intra Organization Connector (IOC) Organization Relationship Availability Address Space Pure Exchange 2016 Hybrid YES (created automatically by HCW) YES YES Pure Exchange 2013 (CU5+) Hybrid YES (created automatically by HCW) YES YES Pure Exchange 2010 Hybrid NO YES YES Mixed Exchange 2007 + Exchange 2010 Hybrid NO - Ex2010 NO - Ex2007 YES - Ex2010 NO - Ex2007 YES - Ex2010 YES - Ex2007 Mixed Exchange 2007 + Exchange 2013 Hybrid YES - Ex2013 (if created manually) NO - Ex2007 YES - Ex2013 NO - Ex2007 YES - Ex2013 YES - Ex2007 Mixed Exchange 2010 + Exchange 2013 Hybrid YES - Ex2013 (if created manually) NO - Ex2010 YES - Ex2013 YES - Ex2010 YES - Ex2013 YES - Ex2010 Mixed Exchange 2010 + Exchange 2016 Hybrid YES - Ex2016 (if created manually) NO - Ex2010 YES - Ex2016 YES - Ex2010 YES - Ex2016 YES - Ex2010 Mixed Exchange 2013 + Exchange 2016 Hybrid YES - Ex2016 (created automatically by HCW) YES - Ex2013 YES - Ex2016 YES - Ex2013 YES - Ex2016 YES - Ex2013 Note: OAuth is by default configured by HCW in Exchange 2013 CU5 and above (including Exchange 2016) organizations. If Exchange 2013 / Exchange 2016 servers coexist with Exchange 2010 or older then OAUTH is not configured by default by the HCW but can be manually configured. Note: Exchange 2013 CU5 is considered old and unlike wine, the finest CU is always the most recent one. You probably have heard about our n and n-1 supported version statement in Hybrid Deployments and can read more about it here and here. Which Free/Busy lookup method are you using? I won't go into all the details about the two types of authentication (OAUTH vs DAUTH) in this post, but I recommend reading this blog post at bedtime: Deep Dive: How Hybrid Authentication Really Works. As explained there, OAuth is an open-standards based model which is more preferred to a customized model. You can quickly determine if you are using OAuth or not by running: Get-IntraOrganizationConnector cmdlet in Exchange Management Shell (for F/B direction On-Premises to Cloud) and in Exchange Online PowerShell (for F/B direction Cloud to On-Premises). If you see Enabled = True, then you are using OAuth or the system should at least be trying to. Note: We also need to make sure that the Target Domain is present on the Intra Organization Connector or Organization Relationship when deciding if using OAUTH or DAUTH. I have created two flowcharts to show you the logic of using OAUTH vs DAUTH in a F/B lookup process for each F/B direction. The user’s setup remains still the same as shown in previous examples and I am reposting the diagram here so that you don’t need to scroll up. 1. Joe’s Exchange server deciding whether to use Oauth or Dauth : 2. Jane’s Exchange Online server deciding whether to use Oauth or Dauth Now that you know which method is being used (or at least which should be attempted) and we know the direction Free/Busy is failing, we can see if you have everything configured correctly. In most cases these configurations are handled by the HCW and should be accurate and you can re-run the HCW to get things back to a good configuration. If Exchange On-Premises > Exchange Online Free/Busy is failing for all users, you would first check Intra Organization Connector or the Organization Relationship from on-premises. If Exchange Online > Exchange On-Premises Free/Busy is failing for all users, you would first check Intra Organization Connector or the Organization Relationship from Exchange Online. Below, you will see a sample of the expected configuration for Intra Organization Connectors and Org Relationships from both sides (on-premises and cloud). This Baseline configuration was documented by my co-worker Ray Fong (Support Escalation Engineer) and I am very happy to have it when I troubleshoot Free/Busy issues. Exchange Online side Use this article to connect to Exchange Online PowerShell. INTRA ORGANIZATION CONNECTOR IN CLOUD Get-IntraOrganizationConnector | fl TargetAddressDomains,DiscoveryEndpoint,Enabled TargetAddressDomains : {contoso.com} DiscoveryEndpoint : https://autodiscover.contoso.com/autodiscover/autodiscover.svc * Enabled : True Note: In practice, the On-Premises Discovery Endpoint (Autodiscover) is more likely to be found in the format https://mail.contoso.com/autodiscover/autodiscover.svc because of the EWS External URL, so pay attention to this Autodiscover URL and replace it if needed with the autodiscover.yourdomain.tld on the IOC present in the Cloud Side (Reference Set-IntraOrganizationConnector) Get-IntraOrganizationConfiguration | fl OnPremiseTargetAddresses OnPremiseTargetAddresses : {contoso.com} TargetAddressDomains - This should be your federated domains. Example: contoso.com You can find the domains name by cross-checking Exchange Online's (Get-IntraOrganizationConfiguration).OnPremiseTargetAddresses TargetDiscoveryEndpoint - This should be the address of the On-Premises Autodiscover Endpoint. Example: https://autodiscover.contoso.com/autodiscover/autodiscover.svc/.If you paste the URL in IE, you should receive a regular windows authentication security prompt Enabled - This must be True. Exchange On-Premises side (use Exchange Management Shell) INTRA ORGANIZATION CONNECTOR IN ON-PREM Get-IntraOrganizationConnector | fl Name,TargetAddressDomains,DiscoveryEndpoint,Enabled Name : ExchangeHybridOnPremisesToOnline TargetAddressDomains : {contoso.mail.onmicrosoft.com} DiscoveryEndpoint : https://outlook.office365.com/autodiscover/autodiscover.svc Enabled : True TargetAddressDomains - This should be your tenant.mail.onmicroosft.com name. Example: 'contoso.mail.onmicrosoft.com' TargetDiscoveryEndpoint - This should be the address of EXO Autodiscover endpoint. Example: https://outlook.office365.com/autodiscover/autodiscover.svc Enabled - This must be True. Exchange Online side Use this article to connect to Exchange Online PowerShell. ORGANIZATION RELATIONSHIP IN CLOUD Get-OrganizationRelationship "Exchange Online to on premises Organization Relationship" | fl DomainNames,FreeBusy*,Target*,Enabled DomainNames : {contoso.com} FreeBusyAccessEnabled : True FreeBusyAccessLevel : LimitedDetails FreeBusyAccessScope : TargetApplicationUri : FYDIBOHF25SPDLT.contoso.com TargetSharingEpr : TargetOwaURL : TargetAutodiscoverEpr : https://autodiscover.contoso.com/autodiscover/autodiscover.svc/WSSecurity Enabled : True DomainNames - This should be your federated domains. Example: contoso.com You can find the domains name by cross-checking On-Premises' (Get-FederatedOrganizationIdentifier).Domains TargetAutodiscoverEPR - This should be the address of the On-Premises Autodiscover Endpoint. Example: https://autodiscover.contoso.com/autodiscover/autodiscover.svc/WSSecurity. If you paste the URL in IE, you should receive a regular windows authentication security prompt TargetSharingEPR - Ideally this is blank. If it is set, it should be the On-Premises Exchange servers EWS ExternalUrl endpoint. Example: https://server.contoso.com/EWS/Exchange.asmx You can find the URL by cross-checking On-Prem's Get-WebServicesVirtualDirectory ExternaUrl. If you paste the URL in IE with /WSSecurity at the end (https://server.contoso.com/EWS/Exchange.asmx/WSSecurity), you should receive a regular windows authentication security prompt TargetApplicationURI - This must match the ApplicationUrI from On-Prem. Example: FYDIBOHF25SPDLT.contoso.com You can find the value by cross-checking On-Prem's (Get-FederationTrust).ApplicationUri FreeBusyAccessEnabled - This must be True. FreeBusyAccessLevel - This should be either AvailabilityOnly or LimitedDetails. AvailabilityOnly: Free/Busy access with time only LimitedDetails: Free/Busy access with time, subject, and location FreeBusyAccessScope - This is typically blank. The FreeBusyAccessScope parameter specifies a security distribution group in the internal organization that contains users that can have their Free/Busy information accessed by an external organization. Enabled - This must be True. Exchange On-Premises side (use Exchange Management Shell) ORGANIZATION RELATIONSHIP IN ON-PREM Get-OrganizationRelationship "On Premises to Exchange Online Organization Relationship" | fl DomainNames,FreeBusy*,Target*,Enabled DomainNames : {contoso.mail.onmicrosoft.com} FreeBusyAccessEnabled : True FreeBusyAccessLevel : LimitedDetails FreeBusyAccessScope : TargetApplicationUri : Outlook.com TargetSharingEpr : TargetOwaURL : https://outlook.com/owa/contoso.onmicrosoft.com TargetAutodiscoverEpr : https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc/WSSecurity Enabled : True DomainNames - This should be your tenant.mail.onmicrosoft.com name. Example: contoso.mail.onmicrosoft.com TargetAutodiscoverEpr - This should be a valid Exchange Online Autodiscover endpoint. Example: https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc/WSSecurity or https://pod51038.outlook.com/autodiscover/autodiscover.svc/WSSecurity [<-- A pod address] You can find the value from TargetAutodiscoverEpr of Get-FederationInformaiton -DomainName tenantname.mail.onmicrosoft.com -BypassAdditionalDomainValidation | fl TargetSharingEPR - Ideally this is blank. If it is set, it should be Office 365 EWS endpoint. Example: https://outlook.office365.com/EWS/Exchange.asmx TargetApplicationURI - This must be outlook.com if this is for organization relationship of the cloud tenant. For non-cloud organization relationship, this must match (Get-FederationTrust).ApplicationUri of the On-Prem trust of the other organization. FreeBusyAccessEnabled - This must be True. FreeBusyAccessLevel - This should be either AvailabilityOnly or LimitedDetails. AvailabilityOnly: Free/Busy access with time only LimitedDetails: Free/Busy access with time, subject, and location FreeBusyAccessScope - This is typically blank. The FreeBusyAccessScope parameter specifies a security distribution group in the internal organization that contains users that can have their Free/Busy information accessed by an external organization. Enabled - This must be True. Both Autodiscover and EWS virtual directories must be enabled for WSSecurity authentication and/or OAuth. For example, if using OAuth, you should have OAuth listed as Authentication Methods, whereas if using only DAuth (Exchange 2010 for example), you would see only WSSecurity. Example of virtual directories authentication methods for an Exchange 2013 Hybrid Organization: Get-AutodiscoverVirtualDirectory -Server SERVER01 | fl Name,AdminDisplayVersion,*authentication* Name : Autodiscover (Default Web Site) AdminDisplayVersion : Version 15.0 (Build 1044.25) InternalAuthenticationMethods : {Basic, Ntlm, WindowsIntegrated, WSSecurity, OAuth} ExternalAuthenticationMethods : {Basic, Ntlm, WindowsIntegrated, WSSecurity, OAuth} Get-WebServicesVirtualDirectory -Server server01| fl Name,AdminDisplayVersion,*Authentication* Name : EWS (Default Web Site) AdminDisplayVersion : Version 15.0 (Build 1044.25) InternalAuthenticationMethods : {Ntlm, WindowsIntegrated, WSSecurity, OAuth} ExternalAuthenticationMethods : {Ntlm, WindowsIntegrated, WSSecurity, OAuth} As explained earlier, there are some situations where Free/Busy from on-premises to cloud is going via Availability Address Space. This would be the expected configuration for Availability Address Space in Exchange on-premises (Exchange Management Shell): Get-AvailabilityAddressSpace contoso.mail.onmicrosoft.com | fl ForestName, UserName, UseServiceAccount, AccessMethod, ProxyUrl, Name ForestName : contoso.mail.onmicrosoft.com UserName : UseServiceAccount : True AccessMethod : InternalProxy ProxyUrl : https://server01.contoso.com/EWS/Exchange.asmx Name : contoso.mail.onmicrosoft.com ForestName - The should be the tenant.mail.onmicrosoft.com domain name. This should also match the domain name of RemoteRoutingAddress of remote mailboxes. Example: contoso.mail.onmicrosoft.com UserName - This should be blank. UserServiceAccount - This must be True. AccessMethod - This should be InternalProxy. ProxyUrl - This should be the Exchange 2013/2016 Exchange Web Services Virtual Directory URL. The address could be the internal FQDN or load balancing EWS URL. Example: https://server01.contoso.com/EWS/Exchange.asmx We recommend you check the following requirements for inbound/outbound connectivity to and from Exchange servers in a Hybrid Deployment: Understanding Federated Delegation Office 365 URLs and IP address ranges If you have read this far – thank you! This concludes the Part 1 of this blog series. Onto troubleshooting next! Huge thanks to all that contributed to this blog post: Ray Fong, Nino Bilic, Tim Heeney, Greg Taylor and Brian Day. Mirela BuruianaDemystifying Hybrid Free/Busy: Finding errors and troubleshooting
EDIT 9/19/2023: This blog post has received significant update. In this second part of the Demystifying Hybrid Free/Busy, we will cover troubleshooting of Hybrid Free/Busy scenarios, more specifically – how and where to find an actual error that will indicate where the problem is. Before venturing forth, please make sure that you have seen Part 1 of this demystifying series! Here is the graphics we posted in the previous post; use this as a reference for users that we will be referring to when troubleshooting: Do you really have a Free/Busy issue? Usually when a user creates a new meeting in Outlook on the web (OWA) or Outlook, clicks on Scheduling Assistant, adds his or her colleague to the meeting, they try to see when the user is available to meet. If they see the hash marks \\\\\\\ instead of seeing if the other user is free or busy, there is an issue. Here, we do seem to have a bunch of Free/Busy issues: You can often see an error message by hovering over hash marks, however we usually find that the error is not very specific. Instead, we would need to take slightly more advanced steps to diagnose the issues by checking things like the Remote Connectivity Analyzer tool, Fiddler, F12 Network tab, Outlook logging or SARA tool. Where is the actual Free/Busy error message? First, we need to understand in which direction we have a lookup problem. Please see Part 1 for discussion of directionality. Sources of logs: Remote Connectivity Analyzer tool Outlook logging SARA tool OWA F12 Network Tab Fiddler – Outlook and OWA These steps are important for us to see the relevant message error for Free/Busy issues. Once we know the error message, it’s much easier to resolve the issue. Remote Connectivity Analyzer A few things to know about this tool: Source Mailbox: the user that will be requesting the free/busy information. This will be the user that is logged in Outlook or OWA and cannot see free/busy for other people. This is also called Requester or Organizer of the meeting. Authentication type for Source Mailbox: you will choose Modern Authentication Source Mailbox credentials: you will need to authenticate with the credentials of the Source Mailbox. The tool doesn’t support Basic Authentication for Exchange Online mailboxes because this is disabled in Exchange Online. While it is still used by Exchange On-premises environments, currently, if you select Basic Authentication for the on-premises source mailbox, the test will fail before doing the actual Free/Busy process. It works if your Exchange on-premises has enabled Modern Authentication for client protocols. In conclusion, Source Mailbox login needs to be using OAuth for this test to work, regardless of where it is hosted. Target Mailbox: the user that the Source Mailbox is requesting free/busy for. This is the Attendee of the meeting. The tool simulates Outlook’s way of querying Free/Busy. If you have a free/busy issue that is only happening in OWA but not in Outlook Desktop, then this test will likely not catch the error. To be able to perform the test, you must allow connectivity for the Remote Connectivity Analyzer tool’s IP addresses. These are part of the "Microsoft 365 Common and Office Online" ranges published in the Office 365 URLs and IP address ranges. The IPs for the Remote Connectivity Analyzer are part of the range specified as "Allow Required" (currently ID 46 in the documentation). Check https://testconnectivity.microsoft.com/Pages/ChangeList.htm for any future changes. Note that you can only insert one Target Mailbox email address per test. If you have errors for multiple target mailboxes, run multiple tests, for each user. Connectivity Test Results: With these 3 buttons on the top right corner, you can expand all the results and save them as XML or HTML files. Usually, support people appreciate these files a lot, so please do upload them in your support case workspace. When you expand the results, there are 3 important checks: Determining where the source mailbox is hosted (cloud or not). If the Mailbox is hosted in cloud, you will see something like this: IsOffice365Mailbox=True. The mailbox is hosted in Office 365. <ASURL>https://outlook.office365.com/EWS/Exchange.asmx</ASURL> If the Mailbox is not hosted in cloud, you will see something like this: IsOffice365Mailbox=False. The mailbox isn't hosted in Office 365. Determining where the target mailbox is hosted (cloud or not). Test Autodiscover for the Target Mailbox SMTP to retrieve External EWS url. Quick tip: on your side, in Windows PoweShell, you can also use the following commands to see the External EWS url of an user based on the Autodiscover call to Office 365, replace what is in Email= with your actual email addresses. Invoke-RestMethod -Uri "https://outlook.office365.com/autodiscover/autodiscover.json?Email=CLOUDUSER@CONTOSO.COM&Protocol=EWS" Invoke-RestMethod -Uri "https://outlook.office365.com/autodiscover/autodiscover.json?Email=ONPREMUSER@CONTOSO.COM&Protocol=EWS" Performing the Free/Busy Lookup. This will be Success or Failed. If it failed, look under the Additional details to see the error message. If success, be happy, maybe the issue is resolved, or not be happy as it might be an intermittent issue (which is harder to troubleshoot) or a local issue only (happening in your specific network, machine, Outlook version). In my case, I see that I have a NoFreeBusyAccessException, given by the Exchange on-premises server HHE1601. OUTLOOK Note: The Modern Outlook clients log Free/Busy information in Outlook ETL files and you won’t be able to see the Free/Busy error in plain text here. This was possible with Outlook 2010 logs, back in the old days. But this method is still useful, because you can provide the Outlook ETL log containing the error to Microsoft Support to parse it for you and help you fix it also. If you want to see the error for yourself, check the Fiddler method. For the Outlook F/B error, we need to first enable Outlook logging and after this we will need to reproduce the issue (\\\\\\). After repro, we will collect the Outlook logs. Steps: Enable Outlook logging: Follow this KB article and check the “Enable troubleshooting logging (this requires restarting Outlook)” option. Restart Outlook. Reproduce the issue for the non-working free/busy direction. Suppose Free/Busy direction not working is cloud to on-premises, you will be logged on as a cloud user (Source Mailbox), go to Calendar tab, New Meeting, Scheduling Assistant, add some on-premises users to a meeting until you see the hash marks (instead of Free/Busy information). You do not need to save or send a meeting request. Collect the Outlook-#####.etl log from %temp%\Outlook Logging folder (reference here). You would need to send the ETL file to Microsoft Support to get it analyzed as we are parsing this log with an internal tool. You might not know this, but Hybrid free/busy support cases are free of charge! Of course, you can still use the other methods (fiddler for Outlook/OWA or browser for OWA) to see Free/Busy error yourself, however we (Support) might ask you additionally to get this log as well for a further dive into the Free/Busy errors. SARA I would also like to mention that there is a Free/Busy troubleshooter in Beta version, incorporated into SARA tool (Microsoft Support and Recovery Assistant for Office 365) which you can download it from here : https://diagnostics.outlook.com/#/ Open SARA and select Outlook scenario, click Next, then select I’m having problems with my calendar, input email address and password of the source mailbox (cloud mailbox if direction not working is cloud > on-premises) and then select I can’t see when someone is free or busy. Due to the underlying complexity of it all, this is not a completely reliable way of determining the cause of free/busy issues in Hybrid Deployments, but it is a good start when troubleshooting. This F/B test from SARA covers mostly cloud to cloud scenarios but I recommend it here because it does connectivity and additional checks on tenant, licensing and Autodiscover. And sometimes it shows the underlying Free/Busy error message. Here are some screenshots with the SARA process: After the Office 365 readiness checks, the tool will ask you for the email address of the Target Mailbox: In the failed results, expand the Support Message and User Message: OWA / Outlook on the web F12 Network Tab Cloud OWA F12 Network tab You need to login to OWA as the source mailbox, hit F12 (Developer Tools for browser) and select the Network Tab. You would then lookup Free/Busy for the target mailbox (reproduce the issue). If the source mailbox is hosted in Cloud, to look for the F/B here, you can find the Search Icon and type there “GetSchedule” or find the Filter Icon and type “graphql”, then look at Response or Preview tab to see the error message by expanding GetSchedule until you reach to the error. (click thumbnail to view larger) If the Source Mailbox is hosted in Exchange On-Premises, you would look after GetUserAvailabilityInternal: Fiddler –Outlook or OWA You would need to download and install Fiddler tool from the internet, enable HTTPS decryption in Fiddler and then reproduce the Free/Busy issue in Outlook or OWA or both. Fiddler - Exchange Online Source Mailbox logged in Outlook desktop. Look for “GetUserAvailability” calls and then on the right side, you have Request on the top and Response on the bottom. Switch to XML tabs for a nicer view. In the Request you will see the attendees’ email addresses and, in the Response, you will have ResponseMessage with ResponseClass=Error or ResponseClass=Success. Fiddler – Exchange Online Source Mailbox logged in OWA. In Fiddler, you can check in the Request pane, under Raw tab the ClientRequestID, you can for example search after this specific value in your on-premises Exchange server logs: IIS W3SVC2 logs, HTTPProxy EWS logs and EWS logs (more information on these logs, location and extracts, later in the article). Example here from a lab: ClientRequestID: {72741DFF-A6AC-402B-991B-C6B5D56B1422} Date: Mon, 11 Sep 2023 19:01:25 GMT If you are fan of SQL language, you can use a tool like Log Parser Studio and search through these logs, for example, here is a query on the ClientRequestID from earlier: SELECT DateTime, ClientRequestID, RequestID, UserAgent, SoapAction, ErrorCode, GenericErrors, GenericInfo, FileName FROM '[LOGFILEPATH]' WHERE ClientRequestID LIKE '%{72741DFF-A6AC-402B-991B-C6B5D56B1422}%' You can also use findstr.exe utility to look for the client request id or other keywords like the requester’s email address or “CrossForest”. Example of command: findstr.exe /I /S "{72741DFF-A6AC-402B-991B-C6B5D56B1422}" *.log When troubleshooting Free/Busy issues, the following on-premises logs can be very useful, especially for Cloud to On-Premises Free/Busy direction. IIS logs Default Web Site (DWS) Path: %SystemDrive%\inetpub\logs\LogFiles\W3SVC1 Path example: C:\inetpub\logs\LogFiles\W3SVC1 Extract of Autodiscover and EWS log entries with IOC Enabled in IIS W3SVC1 logs: Autodiscover – OAUTH (autodiscover.svc without /WSSecurity) 2016-01-06 17:45:27 10.0.0.5 POST /autodiscover/autodiscover.svc &CorrelationID=<empty>;&ClientId=QNFNHKEEKYENCJITQQ&cafeReqId=7972d1fc-a9d9-44c6-8851-480d3601cbd7; 443 S2S~00000002-0000-0ff1-ce00-000000000000 132.245.65.28 ASAutoDiscover/CrossForest/EmailDomain//15.01.0361.007 200 0 0 109 EWS – OAUTH (exchange.asmx without /WSSecurity) 2016-01-06 17:45:27 10.0.0.5 POST /ews/exchange.asmx &CorrelationID=<empty>;&ClientId=WSIVGUUAUWWRFACJBWDA&cafeReqId=6ce8864c-74a0-4ad2-a3dc-7b69e0415403; 443 <unverified>actas1(sip:joe@contoso.com|smtp:joe@contoso.com|upn:joe@contoso.com) 132.245.65.28 ASProxy/CrossForest/EmailDomain//15.01.0361.007 200 0 0 703 Example of EWS entry with Organization Relationship Enabled in IIS W3SVC1 logs: EWS – DAUTH (exchange.asmx with /WSSecurity) 2016-01-06 18:04:41 10.0.0.5 POST /ews/exchange.asmx/WSSecurity &CorrelationID=<empty>;&ClientId=VOMGJKAWURSVKOXQLBVA&cafeReqId=18fd3a2e-7b1c-4828-8943-6b20912e2e44; 443 - 132.245.65.28 ASProxy/CrossForest/EmailDomain//15.01.0361.007 200 0 0 296 IIS logs Exchange BackEnd (BE) Path: %SystemDrive%\inetpub\logs\LogFiles\W3SVC2 Path example: C:\inetpub\logs\LogFiles\W3SVC2 Example of EWS entry with Organization Relationship Enabled (DAUTH) in IIS W3SVC2 logs: 2016-01-06 18:04:41 fe80::f17f:beef:a5e3:7d3c%25 POST /ews/exchange.asmx/WSSecurity - 444 - fe80::f17f:beef:a5e3:7d3c%25 ASProxy/CrossForest/EmailDomain//15.01.0361.007 200 0 0 93 HTTPProxy logs for Autodiscover Path: %ExchangeInstallPath%Logging\HttpProxy\Autodiscover Path example: C:\Program Files\Microsoft\Exchange Server\V15\Logging\HttpProxy\Autodiscover Example of Autodiscover entry with Organization Relationship Enabled (DAUTH) 2016-01-06T18:05:20.552Z,bcdfbed5-f11f-4250-a616-e38cb475cd3f,15,0,1104,2,,Autodiscover,autodiscover.contoso.com,/autodiscover/autodiscover.svc /WSSecurity,,,false,,contoso.com,Smtp~joe@contoso.com,ASAutoDiscover/CrossForest/EmailDomain/ /15.01.0361.007,132.245.65.28,exch-2013,200,200,,POST,Proxy,exch-2013.contoso.com,15.00.1104.000,IntraForest,AnchorMailboxHeader-SMTP,[…],BeginRequest=2016-01-06T18:05:20.192Z;CorrelationID=<empty>;ProxyState-Run=None;FEAuth=BEVersion-1941996624;NewConnection=fe80::f17f:beef:a5e3:7d3c%25&0; HTTPProxy logs for EWS Path: %ExchangeInstallPath%Logging\HttpProxy\Ews Path example: C:\Program Files\Microsoft\Exchange Server\V15\Logging\HttpProxy\Ews Example of EWS entry with Organization Relationship Enabled (DAUTH): 2016-01-06T18:04:41.490Z,4757ab2c-8ccc-4d1a-ae39-0780ecc8eabb,15,0,1104,2,{02CD833F-18AB-413A-83CB-0E86F4DA5362},Ews,mail.contoso.com,/ews/exchange.asmx/WSSecurity,,,false,,contoso.com, Smtp~joe@contoso.com,ASProxy/CrossForest/EmailDomain//15.01.0361.007,132.245.65.28,exch-2013,200,200,,POST,Proxy,exch-2013.contoso.com,15.00.1104.000,IntraForest,AnchorMailboxHeader-SMTP,[…],BeginRequest=2016-01-06T18:04:41.380Z; EWS logs Path: %ExchangeInstallPath%Logging\Ews Path example: C:\Program Files\Microsoft\Exchange Server\V15\Logging\Ews Example of EWS entry with Organization Relationship Enabled (DAUTH): 2016-01-06T18:04:41.490Z,4757ab2c-8ccc-4d1a-ae39-0780ecc8eabb,15,0,1104,2,{02CD833F-18AB-413A-83CB-0E86F4DA5362}, External,true,jane@contoso.mail.onmicrosoft.com,, ASProxy/CrossForest/EmailDomain//15.01.0361.007,Target=None;Req=Exchange2012/Exchange2013; ,132.245.65.28,exch-2013,exch-2013.contoso.com,GetUserAvailability,200,12150,,,,,,ebd34d71ac7342c19d947d881db4ad55,f866c73e-6c91-475e-bdec-0428bdeaa423,PrimaryServer; Requester=jane@contoso.mail.onmicrosoft.com; Failures=0 Event Viewer Application logs on Exchange Server References here and here. Example of Event ID 4002 for MSExchange Availability: Log Name: Application Source: MSExchange Availability Event ID: 4002 Task Category: Availability Service Level: Error Description: Process 4568: ProxyWebRequest CrossSite from S-1-5-21-391720751-1508397712-925700815-508779 to https://hybrid.contoso.com/ews/exchange.asmx failed. Caller SIDs: NetworkCredentials. The exception returned is Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequestProcessingException: System.Web.Services.Protocols.SoapException: You have exceeded the available concurrent connections for your account. Try again once your other requests have completed. at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall) IIS tracing for the error code in the IIS logs Reference here. Free/Busy errors and fixes Based on cumulative support team experience, we created a table (see the attachment to this post) with Free/Busy errors encountered so far and their possible resolutions. We cannot cover all possible scenarios and errors even though we have a good-sized list. This is meant to illustrate ways we can resolve specific errors and these suggestions might not work for you even if you have the same error. If you know the exact Free/Busy error that you get and checked configuration as discussed in part 1 of this series, this is already a tremendous progress, and this will help us resolve your issue faster. Of course, you can follow these suggestions on your own as most of the actions are harmless but if you don’t feel confident in troubleshooting on your own or you fear that actions are dangerous or irreversible, please contact us. Free/Busy Errors discussed in the attached document (FB_Errors_FixesV7): “An internal server error occurred. The operation failed” LID: 59916. 500 Internal Server error. "The remote user mailbox must specify the the explicit local mailbox in the header" "An error occurred when verifying security for the message" "Unable to connect to the remote server" “Autodiscover failed for email address <> with error ‘The request failed with HTTP status 404: Not Found’ ” “The request failed with HTTP status 401: Unauthorized - The user specified by the user-context in the token is ambiguous” LID: 43532 "An existing connection was forcibly closed by the remote host - An unexpected error occurred on a receive " "An existing connection was forcibly closed by the remote host - An unexpected error occurred on a send ” "Configuration information for forest/domain could not be found in Active Directory" "Proxy web request failed.,inner exception: The request failed with HTTP status 401: Unauthorized." "The response from the Autodiscover service at 'https://autodiscover/autodiscover.svc/WSSecurity' failed due to an error in user setting 'ExternalEwsUrl'. Error message: InvalidUser." LID: 33676 “The caller does not have access to free/busy data" LID: 47652 LID: 44348 “The request failed with HTTP status 403: Forbidden (The server denied the specified Uniform Resource Locator (URL). “ LID: 43532 “Unable to resolve e-mail address user@notes.domain.com to an Active Directory object” LID: 57660 “An error occurred when processing the security tokens in the message.” LID: 59916 “The cross-organization request for mailbox yyy@contoso.com is not allowed because the requester is from a different organization” LID: 39660 “The request failed with HTTP status 401: Unauthorized - Microsoft.Exchange.Security.OAuth.OAuth TokenRequestFailedException: Missing signing certificate “ “The application is missing a linked account for RBAC roles, or the linked account has no RBAC role assignments, or the calling users account is logon disabled” “The entered and stored passwords do not match“ “The password has to be changed.” “The password for the account has expired” or “Provision is needed before federated account can be logged in” “The request timed out” “The specified member name is either invalid or empty” “The result set contains too many calendar entries” LID: 54796 “The request failed with HTTP status 401: Unauthorized - The token has an invalid signature.” “The request failed with HTTP status 401: Unauthorized - Client assertion contains an invalid signature. [Reason - The key was not found., Thumbprint of key used by client: '<>’ “ “Proxy web request failed., inner exception: Response is not well-formed XML “ “Failed to communicate with https://login.microsoftonline.com/extSTS.srf., inner exception: Unable to connect to the remote server” “Autodiscover failed for E-Mail Address <> with error System.Net.WebException: The remote name could not be resolved: '<>'” “Failed to get ASURL. Error 8004010F” “Proxy web request failed. , inner exception: System.Net.WebException: The request failed with the error message: -- <head><title>Object moved” “The request was aborted: Could not create SSL/TLS secure channel.” “The user specified by the user-context in the token does not exist.";error_category="invalid_user“ “The hostname component of the audience claim value 'https://<>’ is invalid";error_category="invalid_resource“ “Proxy web request failed. , inner exception: System.Net.WebException: The request failed with HTTP status 503: Service Unavailable” “Proxy web request failed. , inner exception: System.Net.WebException: The request failed with HTTP status 504: Gateway Timeout.” Thanks to all that contributed to this content: Ray Fong, Nino Bilic, Tim Heeney, Greg Taylor and Brian Day. Mirela Buruiana
