Recent Discussions
Exchange 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/Reference 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/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/How to Check Distribution Lists for Activity Over the Last 90 Days
The new Get-MessageTraceV2 cmdlet can fetch 90 days of message trace data, which means that we can check for inactive distribution lists using data for the last 90 days instead of being constrained to the last 10 days. This is done by running fetches for nine batches of traffic, each covering ten days. Distribution lists are still important to Exchange Online and Microsoft 365, and it’s good to know which distribution lists are in active use (and how much traffic they get) and which are not. All done with PowerShell. https://office365itpros.com/2026/07/09/inactive-distribution-list-2026/
Exchange Server to Exchange Online Migration: A Pre-Migration Readiness Checklist
Over the years, I have worked on numerous Exchange Server to Exchange Online migration projects alongside Exchange administrators, IT teams, and MSPs. One consistent pattern I have noticed is that most migration issues do not originate during the migration itself — they surface because of gaps in pre-migration readiness. This checklist reflects what I have found most useful before starting any Exchange to Exchange Online migration. Inventory and Assessment Before touching any migration tooling, run a full inventory of your on-premises Exchange environment. This includes the Exchange Server version (2013, 2016, 2019), the number of mailboxes, database sizes, public folders, shared mailboxes, archive mailboxes, and any resource mailboxes such as rooms and equipment. Many teams also forget to document their distribution groups, dynamic distribution groups, and mail-enabled contacts. All of these need to be accounted for before you begin. 2. Active Directory and Entra ID Readiness Check that your Active Directory is clean: no duplicate UPNs, no lingering objects, and no ambiguous legacy Exchange attributes. Verify that Microsoft Entra Connect (formerly AAD Connect) is installed, configured, and synchronizing without errors. Confirm the UPN suffix used in AD matches a verified domain in your Microsoft 365 tenant. Attribute mismatches between on-premises AD and Entra ID are one of the most common causes of post-migration issues with authentication and mail flow. 3. Mail Flow and DNS Document all current MX records and any third-party mail filtering (SEG, anti-spam appliances). Plan whether you will cut over MX during the migration or keep a hybrid mail flow via Exchange connector. Verify SPF, DKIM, and DMARC records are in place for each domain. Applications and devices that use on-premises SMTP relay also need to be identified early — these often get missed and cause disruption after the migration window. 4. Licensing and Tenant Configuration Confirm you have sufficient Exchange Online licenses assigned or ready to assign before the migration starts. Review your tenant for any conditional access policies that may block newly migrated users. Check the Microsoft 365 admin center for any service health issues that could affect the migration window. Also confirm your tenant's default accepted domains and any aliases that need to be added. 5. Coexistence and Hybrid Considerations If you are running a hybrid migration (which is the recommended approach for most organisations with more than a few hundred mailboxes), confirm the Hybrid Configuration Wizard has been run and that the hybrid connector tests pass. Free/busy lookup, OAB distribution, and cross-premises message tracking should all be tested before you move any mailboxes. A common oversight is failing to validate OAuth configuration for modern authentication in hybrid — this affects calendar sharing and delegate access after migration. 6. Data and Backup Before migrating any mailbox, verify that a recent backup of your Exchange databases exists and is recoverable. If you are running a DAG, confirm all database copies are healthy and no replay queues are building up. It is also worth checking the size and age of any archive mailboxes — large archives can significantly extend migration time and should be planned for separately. What patterns have you seen in your environments? Are there specific pre-migration steps that have saved (or cost) you the most time? Happy to discuss further.How to Check Distribution Lists for Activity Over the Last 90 Days
The new Get-MessageTraceV2 cmdlet can fetch 90 days of message trace data, which means that we can check for inactive distribution lists using data for the last 90 days instead of being constrained to the last 10 days. This is done by running fetches for nine batches of traffic, each covering ten days. Distribution lists are still important to Exchange Online and Microsoft 365, and it’s good to know which distribution lists are in active use (and how much traffic they get) and which are not. All done with PowerShell. https://office365itpros.com/2026/07/09/inactive-distribution-list-2026/Reporting Recent Distribution List Changes
A recent discussion about reporting changes to Microsoft 365 groups provoked the question about how to report distribution list changes. The answer is that the same structure can be taken in a PowerShell script to fetch and report data, including the audit records containing the information about the changes, but the actual code is very different. Distribution lists Exchange Online objects and not Entra ID groups… https://office365itpros.com/2026/06/02/distribution-list-changes/Exchange Online to Deprecate Legacy TLS for POP3 and IMAP4
Microsoft will start to refuse inbound IMAP4 and POP3 client connections using legacy TLS versions (1.0 and 1.1) in July 2026. The move is consistent with other projects to remove obsolete or insecure email protocols from Exchange Online to increase the overall security of the online email service. In this article, we examine some methods to understand the POP3 and IMAP4 usage within a tenant. https://office365itpros.com/2026/04/29/legacy-tls-removal/High Volume Email is Generally Available and Ready to Charge
On April 1, Microsoft announced the general availability for the High-Volume Email (HVE) solution together with details of the PAYG charges incurred to send email to internal recipients, which is all that HVE can do. Microsoft will enable HVE charging on June 1, 2026, Before then, you’ll need to create a billing policy and link it to a valid Azure subscription if you want to continue to use HVE. https://office365itpros.com/2026/04/23/hve-ga-charging/Microsoft Limits App Access to Sensitive Message Properties
Microsoft has announced details of a change to app permissions to restrict updates to sensitive message properties (like recipients) without consent for a new advanced mail access permission. If tenants have apps that interact with message properties, including apps developed by third parties, they should check whether the apps are updating sensitive properties. If so, the new permission must be assigned or the apps will stop working. https://office365itpros.com/2026/03/26/sensitive-message-properties-graph/Microsoft Rushes High-Volume Email to General Availability
Almost two years after it first previewed, Microsoft is making the High-Volume Email (HVE) solution generally available in March 2026. HVE runs on a pay-as-you-go basis, but Microsoft won’t start charging tenants for sending email until May 2026. Two months should be enough for people to decide if they want to use HVE for internal communications as it has no ability to send external email. https://office365itpros.com/2026/03/09/hve-ga/Measuring KPIs like Response Times for Shared Mailboxes
Shared mailboxes are not CRM systems. However, many Microsoft 365 tenants use shared mailboxes to handle customer queries and then want to measure KPIs such as agent responsiveness to customer queries or the number of queries handled per agent in a month. As explored in this article, it’s possible to use the Microsoft Graph and PowerShell to extract some KPI-like data from shared mailboxes. https://office365itpros.com/2026/03/05/shared-mailbox-kpi/Exchange Online PowerShell Dumps the Credential Parameter
On February 12, Microsoft announced the deprecation of the Credential parameter for the Connect-ExchangeOnline cmdlet in the Exchange Online PowerShell module. The deprecation won’t affect interactive sessions (which should all be protected by MFA), but it might stop some background jobs running when Microsoft retires the server components that currently support the ROPC authentication flow. Time to check scripts! https://office365itpros.com/2026/02/16/exchange-online-powershell-ropc/The Final Countdown to Remove EWS from Exchange Online Begins
Microsoft announced the dates leading to the final retirement of Exchange Web Services from Exchange Online. If all goes well, the EWS retirement in the cloud will happen by May 2027. Challenges still exist. Microsoft must remove EWS from its own apps, including Outlook, and help tenants and ISVs make the leap to Graph APIs. Plans are in place and progress is being made, but will everyone be ready when Microsoft starts to remove EWS permanently from Exchange Online in April 2027? https://office365itpros.com/2026/02/06/ews-retirement-may-2027/Using the Exchange Online Message Trace API
January 22 saw the announcement of the beta version of an Exchange Online Graph-based message trace API. The API can retrieve message trace records and their details and offers equivalent functionality to the message trace cmdlets in the Exchange Online management PowerShell module. However, sometimes applications simply want to access data without going through a module, and that’s what this API delivers. The article includes a complete PowerShell script to demonstrate how to use the API. https://office365itpros.com/2026/01/27/message-trace-api/
Modern Auth EWS error 50199 when signing from Crestron Touchpanels
Good Afternoon, All I am having a difficult time nailing down this issue. I have a few Crestron TTS-770s that were, up to last week, working correctly by pulling Calendars data with EWS. They were configured with a service account signed into EWS using 'modern authentication'. This week, these panels have disconnected and report that 'Needs to be authorized' as the EWS status. I have verified that CA is not blocking sign in, the account is excluded from MFA policies, and is correctly licensed for Exchange Access. We do not use Intune for device management. When I attempt to re-register the device, I follow the prompts until I am prompted to close the browser window; The device spins, then fails to connect with the status above. I have attempted this with the service account and my own Admin account with MFA, to the same result. Entra Enterprise Apps Sign-in logs show a 'Successful' entry, then immediately after, a 'Failed' entry with an error '50199'. I had not made changes to any of the URIs before initial failure, and any additional entries or changes do not change the results of the error. Initial URI was configured to 'https://app.noop' (no idea, was configured before I got here, and I hadn't needed to change it), I have attempted combinations of our Tenant URI, ' https://login.microsoftonline.com/common/oauth2/nativeclient', and other 'fixes' I had found while GTS-ing. I additionally have set my 'legacy authentication' and 'legacy applications' CA polices to read-only for troubleshooting. I am working to disable OAuth2ClientProfile on Exchange Online temporarily for troubleshooting. Does anyone have any ideas? Please let me know if any additional information is needed, or if needed to post in another location. Thank YouMicrosoft Cancels Exchange Mailbox External Recipient Rate Limit
After considering customer feedback, Microsoft cancelled the mailbox external recipient rate limit for Exchange Online. The idea behind the new limit was simple – it makes life more difficult for spammers to use Exchange Online as a platform. Unhappily, customers didn’t like losing the ability to send relatively small amounts of external email for different reasons, and Microsoft didn't have a cost-free alternative to offer. C’est la vie. https://office365itpros.com/2026/01/08/mailbox-external-recipient-rate/
Recent Blogs
- We wanted to provide a reminder that Exchange 2016 and 2019 ESU program ends in October 2026.Jul 20, 2026
- We have released Security Updates for Exchange Server SE. Exchange Server 2019 and 2016 ESU updates only.Jul 14, 2026
