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Microsoft Entra Connect 2.x Version Retirement Reminder
Microsoft is retiring older versions of Microsoft Entra Connect Sync 2.x as part of its version lifecycle policy. Version 2.5.79.0 Retirement date: 23 October 2026 This version will retire 12 months after the release of version 2.5.190.0. Important to know Microsoft Entra Connect Sync 2.x versions retire 12 months after a newer version is released. This retirement policy has been in effect since 15 March 2023. For new installations: Always install the latest available version. For existing environments: Plan your upgrade to the latest version before your currently installed version reaches its retirement date.
Exchange SE 15.2.2562.46: MRSProxy returns HTTP 401 after successful NTLM authentication
Hello, Anonymization note: The domain names contoso.com and contoso.local, the server name EXCH-SE-01, and the account name CONTOSO\MigrationAccount used in this post are anonymized placeholders. They do not represent the actual production domain, server, or account names. The Exchange versions, configuration values, HTTP status codes, diagnostic results, and sequence of events are unchanged. We are experiencing an issue with remote mailbox moves from Exchange Server Subscription Edition to Exchange Online. The Exchange Online migration endpoint and the following command both fail: Test-MigrationServerAvailability -ExchangeRemoteMove -RemoteServer "mail.contoso.com" -Credentials $cred The error returned by Exchange Online is: The connection to the server 'mail.contoso.com' could not be completed. The call to: https://mail.contoso.com/EWS/mrsproxy.svc failed with: The HTTP request is unauthorized with client authentication scheme 'Negotiate'. The authentication header received from the server was: 'Negotiate, NTLM'. The remote server returned an error: (401) Unauthorized. Environment Exchange version: Exchange Server Subscription Edition RTM Installed update: August 2026 Security Update KB5121573 Binary version: 15.2.2562.46 Topology: Single Exchange server Mailbox role Classic Full Hybrid Operating system: Windows Server 2022 Exchange Online migration type: Remote Move / onboarding The environment does not have separate frontend and backend Exchange servers. Both the Client Access frontend and mailbox backend services are hosted on the same Exchange server. All checked MRS binaries have the same version: Microsoft.Exchange.MailboxReplicationService.dll Microsoft.Exchange.MailboxReplicationService.Common.dll Microsoft.Exchange.MailboxReplicationService.ProxyClient.dll Microsoft.Exchange.MailboxReplicationService.ProxyService.dll MSExchangeMailboxReplication.exe File version: 15.2.2562.46 MRSProxy configuration Get-WebServicesVirtualDirectory | Format-List Identity, MRSProxyEnabled, BasicAuthentication, WindowsAuthentication, WSSecurityAuthentication, OAuthAuthentication, ExternalUrl Current configuration: MRSProxyEnabled : True BasicAuthentication : False WindowsAuthentication : True WSSecurityAuthentication : True OAuthAuthentication : True ExternalUrl : https://mail.contoso.com/EWS/Exchange.asmx Extended Protection settings have been validated by the latest Exchange Health Checker: Default Web Site/EWS: Extended Protection = Allow SSL flags = Ssl, Ssl128 Authentication = Windows, Negotiate, NTLM Exchange Back End/EWS: Extended Protection = Require SSL flags = Ssl, Ssl128 Authentication = Windows, Negotiate, NTLM Anonymous authentication = enabled Exchange Health Checker reports: Exchange SE RTM Aug26SU Build Number: 15.2.2562.46 MRS Proxy Enabled: True Extended Protection configured correctly for EWS Default Web Site: Started Exchange Back End: Started MSExchangeServicesAppPool: Started Local MRS health All local MRS health checks pass: Get-MailboxServer | Test-MRSHealth | Format-Table Check,Passed,Message -Wrap Results: ServiceCheck : Passed RPCPingCheck : Passed MRSProxyPingCheck : Passed QueueScanCheck : Passed Migration accounts The test was performed with two different on-premises accounts. Both accounts return the same HTTP 401 result. The primary migration account: Enabled : True LockedOut : False PasswordExpired : False The account is also a direct member of: Organization Management One of the accounts used for testing also has domain administrative permissions, so the symptom does not appear to be caused by missing Exchange RBAC permissions. Changing the password and updating the credentials stored in the migration endpoint did not change the result. Failed Request Tracing results Failed Request Tracing was enabled temporarily for Default Web Site. The MRSProxy request is processed in three stages. Stage 1: anonymous request The initial anonymous request to: /EWS/mrsproxy.svc returns HTTP 401, which appears to be the expected authentication challenge. Stage 2: NTLM negotiation The next request shows: WindowsAuthenticationModule AUTH_SSPI_CONTINUE_NEEDED HTTP 401.1 0x8009030e This also appears to be the normal intermediate NTLM challenge. Stage 3: authenticated request The final request shows: Authentication type : Negotiate NTLMUsed : true AUTH_SUCCEEDED : true RemoteUserName : DOMAIN\MigrationAccount AuthUserName : DOMAIN\MigrationAccount The Exchange frontend also calculates the expected backend server. However, after authentication succeeds, the request ends with: ModuleName : ManagedPipelineHandler Notification : EXECUTE_REQUEST_HANDLER HttpStatus : 401 HttpSubStatus : 0 ErrorCode : 0 Therefore, Windows Authentication appears to complete successfully. The final HTTP 401 is returned later, while the Exchange/WCF MRSProxy handler is executing. No corresponding failed domain logon events are recorded in the Windows Security log. No new ASP.NET event stating: MRS proxy service is disabled is generated for the current requests. Additional checks already completed We have already verified the following: MRSProxyEnabled=True Test-MRSHealth passes Two migration accounts tested Migration account is in Organization Management Basic Authentication enabled temporarily for testing Windows Authentication enabled Negotiate and NTLM providers present Frontend Extended Protection set to Allow Backend Extended Protection set to Require Frontend TLS certificate valid Backend port 444 certificate valid MSExchangeServicesAppPool running Mailbox Replication Service running EWS physical paths valid WCF *.svc handler mapping present MRS binaries present and version-consistent Exchange server fully restarted IIS restarted MRSProxy disabled and enabled again Temporarily enabling Basic Authentication did not change the result. Using another migration account did not change the result. The dedicated Exchange hybrid application and Microsoft Graph hybrid flow are also configured and Test-OAuthConnectivity succeeds. We understand that this configuration is not used for MRS remote mailbox moves. August 2026 SU known issue We reviewed the Exchange Team announcement for the August 2026 Security Update. The article mentions that MRS migrations can fail if a backend mailbox server has the August 2026 SU while the frontend Exchange server proxying the connection is on an older build. This does not seem to match our topology because this is a single Exchange server and all MRS components are on version 15.2.2562.46. The error is also HTTP 401 rather than TooManyTransientFailureRetriesPermanentException. Questions Has anyone observed the following behavior after installing Exchange SE August 2026 SU, KB5121573? MRSProxyEnabled=True Test-MRSHealth passes NTLM authentication reaches AUTH_SUCCEEDED ManagedPipelineHandler returns final HTTP 401.0 Test-MigrationServerAvailability fails In particular: Is there a known issue in KB5121573 related to MRSProxy authorization after successful NTLM authentication? Does MRSProxy require any additional authorization configuration introduced by the August 2026 security changes? Is there a supported way to validate the MRSProxyAuthorizationManager decision? Are there additional diagnostic logs that show why the WCF MRSProxy handler returns HTTP 401 after AUTH_SUCCEEDED? Is reapplying KB5121573 the recommended repair action in this situation? Has anyone resolved the issue without recreating the EWS virtual directory or disabling Extended Protection? We have retained the following diagnostic evidence and can provide sanitized excerpts: Exchange Health Checker TXT/XML Test-MigrationServerAvailability output Test-MRSHealth output Frontend EWS Failed Request Tracing EWS HttpProxy logs EWS and backend IIS configuration MRS binary versions and hashes Any guidance or confirmation from the Exchange Team or administrators who encountered the same behavior would be appreciated. Thank you.
HELP - cannot add email to the exchange with outlook classic 2021 and 2024
We have recently upgraded and have a exchange email accounts. We have tried to add emails to connect through exchange we constantly get this error message The action cannot be completed. The name cannot be matched to a name in the address list. We have searched and undertaken many things to and still says this, would anyone know how to fix this?Primary Mailbox Quota Increases to 100 GB for Microsoft 365 Business Plans
Microsoft announced details about how they will deploy the 100 GB mailbox quota to Microsoft 365 Business tenants. A new service plan is being deployed to tenants to liberate the additional 50 GB of quota. Having a larger mailbox quota delivers a fantastic opportunity to fill a mailbox with all sorts of digital debris, something that can cause problems in the era of AI. Perhaps enabling mailbox archiving for Business tenants to allow them to clear out old mailbox items would have been better? https://office365itpros.com/2026/08/21/100-gb-mailbox-quota-m365-business/
Anyone else seeing mailboxes with Exchange Online 2 showing they now have 150gb?
Noticed this this morning. I understand that Basic was going to go to 100gb as they roll that out, but did they also increase Exchange 2 to 150gb to make it still worth paying for it vs an archive license? Or is this a glitch that is going to give us a problem later when people blow through the limit and MS corrects it? This example mailbox is licensed with Business Basic, then Exchange Online added on. It now shows 150gb. I'm seeing this for every user in every tenant I have looked at so far.
Using a scanner device with HVE
Has anyone had any success in setting up a scanner device with HVE? Everything I've read about the HVE option allows for a scanner to send to HVE, but as I've had no luck in getting my Brother ADS-2800 to communicate with HVE. I've confirmed the settings multiple times, but keep getting the same error when I attempt a test email from the scanner. " Communication over the network using SSL was unsuccessful. The SSL settings may not be configured to match the server settings. Confirm the send e-mail server "Port" and the setting for "SSL/TLS". We'd like to use these scanners for sending into a pre-designated internal mailbox. In theory it should work - in practice however, different story.Get-EXOMailbox -Filter returns empty when $WarningPreference = 'SilentlyContinue'
Get-EXOMailbox -Filter returns empty when $WarningPreference = 'SilentlyContinue' under UAMI app-only auth Module version: ExchangeOnlineManagement 3.x (PS7, Azure Automation sandbox) Auth method: Connect-ExchangeOnline -ManagedIdentity -ManagedIdentityAccountId <UAMI ClientId> Reproduction steps: $WarningPreference = 'SilentlyContinue' Connect-ExchangeOnline -ManagedIdentity ` -ManagedIdentityAccountId "<UAMI-ClientId>" ` -Organization "yourtenant.onmicrosoft.com" ` -ShowBanner:$false # Returns empty — mailbox provably exists Get-EXOMailbox -Filter "ExternalDirectoryObjectId -eq '<EntraOID>'" # Restore and retry — returns correctly $WarningPreference = 'Continue' Get-EXOMailbox -Filter "ExternalDirectoryObjectId -eq '<EntraOID>'" Expected: Mailbox object returned regardless of $WarningPreference Actual: Returns $null when $WarningPreference = 'SilentlyContinue' Notes: Only affects -Filter parameter under app-only/UAMI auth -Identity and -UserPrincipalName are not affected Delegated auth sessions are not affected $WarningPreference = 'SilentlyContinue' is a common pattern in Azure Automation runbooks, making this a significant undocumented breaking behaviour for automation scenarios
HCW - Hybrid Configuration Wizard for Hybrid Certificate
I've gone through about 5 Microsoft Exchange Support Engineers for last two years with Exchange on-line migration and 80% of time running HCW, it caused email outages where the engineers did not know what to do. They've also gave conflicting information on how to correctly run HCW for adding server and to replace certificate. Some say use powershell and some says do not use powershell. Now, I need to replace the hybrid certificate, do I uncheck everything and check only "Update Secure Mail Certificate for connectors" in a centralized transport setup (email flows through on-prem servers) ? I assume uncheck everything will not roll back configurations. I have Microsoft Exchange engineers says it will and some say it won't and they all say they have 20+ experience.Outlook - Online mode address book search fails with "Operation failed" when Name only is ticked.
I hope you had this issue and managed to solve 😂 pulling my hair already. Symptom: In classic Outlook for Windows, open the Address Book → set Search to Name only → type any single character → "The address book operation failed." Switch to More columns and the exact same search works fine. Ctrl+K resolution in the To: field works. OWA people search works. Mail flow is fine. It's only the Name-only ANR seek in the dialog. Environment: Exchange hybrid, mailbox in Exchange Online, dir-syncedfrom on-prem AD via Entra Connect Classic Outlook for Windows, online mode (Cached Mode is not permitted here — this is the constraint, I can't just flip it) Affects all users, all machines What I've already ruled out: Test Result Other address lists (Contacts, All Users) Same failure Ctrl+K in To: field Works Safe mode (outlook.exe /safe) Same failure — not add-ins Multiple accounts / multiple machines Same failure Brand-new mail profile Same failure — not profile corruption Addressing order (Tools > Options) GAL set first, not "Choose automatically" Off corporate network (5G) Same failure AddressBookPolicy / OfflineAddressBook on mailbox Both blank (inherit defaults) Get-OfflineAddressBook Default OAB, IsDefault: True, web dist enabled Get-GlobalAddressList Default GAL, IsDefaultGlobalAddressList: True, stock default RecipientFilterImport Bulk PST to Office 365 Step by Step | Stellar Migrator for Outlook
Learn how to import bulk PST files to Office 365 (Exchange Online) step by step using Stellar Migrator for Outlook. This tutorial walks you through automating the migration of multiple PST mailboxes to Exchange Online — no manual uploads, no scripting. Stellar Migrator for Outlook automates bulk PST-to-Office 365 migration, letting you map source PSTs to target Office 365 mailboxes (Primary, Archive, or Public Folder), apply filters, and run the whole job with minimal effort — without worrying about duplicate emails. It's a reliable way to move legacy mailboxes into Office 365. Using a CSV file, you can migrate unlimited PST files to Office 365 users from the same system or across networked systems. The software also supports incremental migration, so you can resume or re-run a job and only new items get imported — no duplicates, no reprocessing what's already migrated. Learn more: https://www.stellarinfo.com/import-pst-to-office-365.phpExchange Online PowerShell Updates to 3.10.1 to Fix CBA
Microsoft rushed out version 3.10.1 of the Exchange Online management PowerShell module to fix a problem with certificate-based authentication. It seems like a change in an internal Microsoft identity platform caused the tokens issued after a successful connection to Exchange Online to not authorize the execution of further cmdlets. To their credit, Microsoft fixed the issue, but is this the kind of thing that should be caught in testing? https://office365itpros.com/2026/07/27/exchange-online-management-3-10-1/
Apple Mail EWS sync intermittent after EwsEnabled=True + AppID allow list
We're a small Microsoft 365 Business tenant (Exchange Online Plan 1/2 mix). One user's Apple Mail (macOS, Exchange/EWS account) intermittently stops syncing new mail — Connection Doctor shows a healthy green "Connection and login to server succeeded," but Get New Mail/manual fetch and forced Sync All Accounts return nothing new, while the same mail is already present via ActiveSync on the same user's iPhone/iPad. Symptoms recur every 1–3 days after temporarily resolving. Troubleshooting completed so far: - Confirmed autodiscover/External URL correctly resolves to outlook.office365.com/EWS/Exchange.asmx - Confirmed EWS enabled at the mailbox level (Manage email apps in admin center) - Found EwsEnabled was blank/null at the org level — set to $true via Set-OrganizationConfig - Configured EwsAllowedAppIDs to include Apple's app ID (f8d98a96-0999-43f5-8af3-69971c7bb423, "Apple Internet Accounts") - Fully removed and re-added the Mac Mail account after the above org-level change - Restarted the Mac, tried DNS changes (8.8.8.8/8.8.4.4), ruled out router-level filtering - Verified no antivirus/VPN/security software on this Mac's network Despite all this, the issue persists intermittently. Notably, a second mailbox on the same tenant, used with Apple Mail on a different Mac (different macOS version, different physical location/network), does NOT experience this issue — so it doesn't appear to be a blanket tenant-wide EWS disruption. Given Apple Mail's continued reliance on EWS ahead of the October 2026 phased disablement, and Microsoft's acknowledgment that Apple Mail for Mac is a heavy EWS consumer they're working with Apple to migrate to Graph, I'm wondering: 1. Could this be related to the ongoing "scream test" EWS disruption testing Microsoft has mentioned, and if so, is there a way to check whether a specific mailbox has been included in that testing? 2. Any known differences in EWS session/connection handling between macOS versions that could explain one Mac being affected and not the other? 3. Anything else worth checking tenant-side (throttling policies, CAS mailbox settings, conditional access rules) that could apply per-mailbox rather than tenant-wide? Happy to provide EWS usage report data or run any diagnostic commands if it helps others hitting the same thing before October.account only remote wipe device
Hello, My o365 account is E3. My phone is android, I installed outlook on my phone. I tested to wipe the outlook on my phone with my admin account, but after I click the "account only remote wip1e device", it showed "Saving in progress", then showed a red "X". The client is Outlook for iOS and Android, client type is outlook not EAS. Do I need more steps to wipe outlook on my phone? or a role/permission is missed? Thanks and regards, AdsnowReference Architecture for an On-Premises AI Assistant for Microsoft Exchange.
Bringing Secure AI Capabilities to On-Premises Microsoft Exchange Many organisations continue to operate Microsoft Exchange within their own data centres because of regulatory requirements, data-residency policies, security considerations, operational dependencies, or the need to maintain complete control over sensitive email information. At the same time, users increasingly expect Artificial Intelligence to help them manage growing email volumes, understand long conversation threads, locate information quickly, analyse attachments, and prepare relevant responses. This creates an important question: Can organisations introduce AI-assisted email capabilities without migrating their on-premises Exchange environment or sending email data to public AI services? With the right architecture, the answer is yes. The opportunity for AI in on-premises Exchange Users spend a significant amount of time reading lengthy email chains, searching for previous discussions, identifying action items, reviewing attachments, and preparing responses. An AI-powered email assistant can help reduce this effort while continuing to operate within the organisation’s controlled infrastructure. Such a solution can be integrated with Microsoft Exchange through an Outlook Web App, or OWA, Add-In. The Add-In provides AI-assisted capabilities within the familiar Outlook Web interface and can be centrally deployed to selected users or Active Directory groups by the Exchange administrator. The purpose is not to replace Exchange or change the way emails are managed. Instead, it introduces an intelligence layer that helps authorised users interact more efficiently with the email information they are already permitted to access. Key capabilities of an AI-powered Exchange Email Assistant 1. Email and conversation summarisation The assistant can summarise an individual email or an entire conversation thread. Instead of reading every message in a long chain, the user can receive a structured summary covering: The purpose of the conversation. Important decisions and commitments. Key action items. Deadlines and pending responses. Relevant information available in attachments. The summarisation process can consider both incoming and sent messages so that the complete context of the conversation is preserved. 2. Contextual draft reply generation The assistant can prepare a suggested response based on the complete email thread and the user’s instructions. Users may select an appropriate tone, such as: Formal. Neutral. Technical. The generated response is placed in the user’s Exchange Draft folder or displayed for review within the OWA Add-In. A critical control is that the AI assistant does not independently send the email. The user remains responsible for reviewing, editing, approving, and sending the response. This human-review approach helps organisations adopt AI while retaining accountability over external and internal communications. 3. Natural-language mailbox search Traditional mailbox search generally depends on exact keywords, sender names, subjects, or date filters. An AI-enabled search experience allows users to search their mailbox using natural-language questions, such as: “Find emails received last month regarding the infrastructure renewal.” “Show unread emails from the finance team that require my approval.” “Find the discussion where the customer confirmed the delivery date.” “Summarise emails from a particular sender concerning the purchase order.” The solution can combine semantic search with traditional keyword-based search to improve the relevance of results. Users can also apply filters such as sender, subject, date range, read or unread status, and conversation thread. 4. Attachment analysis and OCR Important information is often contained within email attachments rather than the email body itself. An on-premises AI assistant can process supported documents, including: PDF files. Microsoft Word documents. Microsoft Excel files. Scanned documents. Image-based attachments. Optical Character Recognition, or OCR, can be used to extract information from scanned or image-based documents. The extracted content can then support email summarisation, contextual draft generation, and mailbox search. For example, a user may ask the assistant to prepare a response based on the commercial terms or delivery date mentioned in an attached document. Maintaining strict mailbox privacy Mailbox privacy is one of the most important architectural considerations for an enterprise AI email assistant. Each user must only be able to access and process emails from their own authorised mailbox. Information retrieved from one user’s mailbox must never become available to another user. This isolation should be enforced across every layer of the solution, including: User authentication. Exchange access tokens. Application sessions. Search indexes. Vector embeddings. AI prompts and responses. Cache and temporary data. Audit logs. The backend should validate the authenticated user and verify mailbox ownership for every request made to Exchange. Where vector search is used, mailbox data should be stored in user-isolated collections, partitions, or namespaces. This helps prevent cross-user retrieval at the data layer rather than relying only on controls within the user interface. Operating without public cloud AI services For organisations with strict security or data-sovereignty requirements, the AI models and supporting components can be deployed within the customer’s infrastructure. A fully on-premises architecture may include: A locally hosted Large Language Model. An on-premises embedding model. A re-ranking model. A vector database. A keyword-search engine. A backend API layer. An OCR or document-intelligence service. A secured OWA Add-In. Integration with Active Directory. Audit, monitoring, and administrative controls. The entire solution can operate within an internal network without sending email content, attachments, prompts, or generated responses to public AI platforms. This model can also support air-gapped environments where internet access is either restricted or completely unavailable. Centralised deployment and administration The OWA Add-In can be deployed centrally through Exchange administration controls. Administrators can assign the Add-In only to selected users or security groups. Employees who are not assigned the solution will not see the AI assistant within their Outlook Web interface. Administrative controls may include: User and group assignment. Enabling or disabling individual AI features. Summarisation-only mode. Draft-generation controls. Attachment-size restrictions. Session and retention policies. Model and performance settings. Usage monitoring. Audit logs. Resource utilisation monitoring. These controls allow organisations to begin with a limited group of users and gradually extend the solution after validating performance, security, and user adoption. Security and governance considerations Introducing AI into an enterprise email environment requires more than deploying a language model. The complete solution should be designed around security, privacy, governance, and responsible AI principles. Important considerations include: Authentication and authorisation The solution should integrate with the organisation’s existing identity infrastructure, such as Active Directory, and enforce role-based access controls. Encryption Email content, attachments, indexes, logs, and other sensitive information should be encrypted both in transit and at rest. Data retention Organisations should clearly define whether AI prompts, generated summaries, and draft content are retained. In privacy-sensitive environments, generated content may remain available only for the active session and should not be permanently stored by the AI application. Auditability The system should record relevant operational events, such as the user identity, requested function, timestamp, and processing status. Depending on the organisation’s policy, the actual email or generated response content may be excluded from audit logs. Human oversight AI-generated responses should be treated as suggestions. The user must review and approve them before sending. The assistant should also disclose its limitations and avoid presenting uncertain outputs as confirmed facts. Performance and capacity On-premises AI processing depends on available compute, memory, storage, and GPU resources. The architecture should account for: Number of concurrent users. Average mailbox size. Volume and size of attachments. Expected response time. Model size. Search-index growth. OCR processing requirements. High availability and backup requirements. A practical adoption approach Organisations do not need to introduce all capabilities at once. A controlled proof of concept can begin with a limited number of users and a defined set of features. A practical implementation sequence may include: Phase 1: Email summarisation Start with individual email and conversation-thread summaries. This provides immediate value while keeping the initial architecture relatively focused. Phase 2: Contextual draft replies Introduce draft generation with mandatory user review and clearly defined tone controls. Phase 3: Attachment processing Enable OCR and document parsing for supported attachments. Phase 4: Intelligent mailbox search Index authorised mailbox content and introduce natural-language search with strict per-user isolation. Phase 5: Wider deployment After security testing, performance validation, and user feedback, extend the solution to additional departments or user groups. Conclusion Organisations operating on-premises Microsoft Exchange do not necessarily need to choose between maintaining control over their email environment and adopting AI-assisted productivity capabilities. A carefully designed on-premises AI email assistant can support email summarisation, contextual draft preparation, attachment analysis, and natural-language mailbox search while keeping sensitive information within the organisation’s infrastructure. The most important success factors are not limited to the AI model itself. Identity controls, mailbox isolation, human approval, auditing, infrastructure sizing, and data-governance policies are equally important. For organisations evaluating private, sovereign, or air-gapped AI, on-premises Exchange can become an effective starting point for introducing practical AI capabilities in a secure and controlled manner. Connect with us to implement this solution in your organization. About the Author Vinay Prakash is the CEO of Glorious Insight and an Ex Microsoft Employee. He works with organisations on Data, Artificial Intelligence, Microsoft cloud technologies, enterprise applications, and secure on-premises AI solutions. For technical discussions related to private or on-premises AI adoption, he can be reached at: Email: email address removed for privacy reasonsThe Demise of the OWA Light Client
On July 8, Microsoft said that they will retire the OWA Light client for Exchange Server in August 2026. But what happened to the OWA Light client for Exchange Online? It seems like Microsoft announced the retirement of OWA Light for Exchange Online in June 2024, but didn’t really make the fact clear in a blog post about consumer accounts. In any case, you can’t run OWA Light for Exchange Online, even if you wanted to. https://office365itpros.com/2026/07/17/owa-light-retirement/Exchange 2019 + ADFS is it possible to configure ModernAuth for third-party Android mail clients?
Hello, Our organization operates under Uzbekistan's data localization and banking secrecy regulations, which require customer and corporate data — including email — to remain on infrastructure physically located within the country and under direct regulatory oversight. This precludes the use of cloud-hosted mail services such as Microsoft 365/Exchange Online, and requires a fully on-premises Exchange deployment with local identity federation (AD FS) instead of Azure AD. Environment: Exchange Server 2019 CU14, single server (MX01), pure on-premises. AD FS is registered as an AuthServer (Type: ADFS), no Azure AD / hybrid tenant involved. The AuthServer is configured correctly: AuthorizationEndpoint and TokenIssuingEndpoint are populated, IsDefaultAuthorizationEndpoint: True, and DomainName points to our mail domain. Realm/ServiceName are configured as well. Symptom: The native iOS Mail client (account added manually, no MDM profile) correctly redirects to our AD FS login page on first setup — the full Modern Auth flow works. A third-party EAS client (Nine by NitroDesk, Android) never receives an OAuth challenge at all — it falls back to Basic authentication. Get-ActiveSyncVirtualDirectory/Set-ActiveSyncVirtualDirectory in this build simply has no -OAuthAuthentication parameter (unlike EWS/OAB). Log finding: When testing with the Nine client, the following was captured in the Exchange HttpProxy/Eas logs: S:ServiceCommonMetadata.OAuthError=Flighting is not enabled for domain 'webmail.<domain>'. S:ServiceCommonMetadata.OAuthErrorCategory=OAuthNotAvailable Questions: What exactly controls "Flighting" for EAS OAuth in a pure on-prem Exchange 2019 CU14 + AD FS scenario (no Azure AD)? Is there a documented, supported way to enable it (New-FlightOverride? something else)? Is EAS Modern Auth even supported for an arbitrary/generic OAuth client (not Apple, not Outlook) in this scenario, or is it effectively an allowlist limited to specific client_ids (Apple Native Mail / Outlook)? How does native iOS Mail get redirected to AD FS without ever receiving an authorization_uri in the EAS/Autodiscover 401 challenge — is there an undocumented discovery path (e.g., hardcoded per registered client_id)? Thank you in advance for any insight.Cross-Tenant Message Recall and Duplicate DDG Detection Enhance Exchange Online Messaging
Last week, the Exchange development team announced two interesting developments. Stopping duplicate dynamic distribution groups and cross-tenant message recall. Preventing tenants from creating duplicate DDLs saves service resources and might make tenants easier to manage. The real value is in cross-tenant message recall, which solves a problem by allowing users to recall messages delivered outside their tenant. The facility only works if the receiving tenant allows, but nothing can be done for messages delivered outside Microsoft 365. https://office365itpros.com/2026/07/15/cross-tenant-message-recall/
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- We wanted to ask how you use Guid, SamAccountName, and DistinguishedName in Exchange Online.Aug 27, 2026
