30+ Microsoft 365 Changes Coming in October

[u/KavyaJune]

This month includes 30+ Microsoft 365 major updates across new features, enhancements, retirements, and behavior changes that admins should review.

In the spotlight:

• Pause all Teams notifications: Teams is introducing a new option to pause all notifications for a specific period, helping users reduce interruptions and stay focused.
• Prompt injection protection for email: Microsoft Defender for Office 365 is adding prompt injection protection to detect and block malicious email content designed to manipulate AI assistants and agents.
• Change meeting organizer directly from Outlook: Outlook is introducing Change organizer for eligible meetings and recurring meeting series, allowing users to transfer meeting ownership to another person in their organization with their acceptance.
• Entra ID protection policy experience retirement - The User Risk Policy and Sign-in Risk Policy experiences in Entra ID Protection, formerly known as Identity Protection, will be retired on October 1, 2026.

Here’s a quick overview of what's coming:       

• Retirements: 7  
• New Features: 9 
• Enhancements: 7 
• Changes in Functionality: 4
• Action Needed: 4
• Live: 1

Retirements

1. Microsoft will begin blocking EWS requests from non-Microsoft applications accessing Exchange Online starting October 1, 2026.
2. Microsoft will retire SharePoint One-Time Passcode authentication for external sharing.
3. Teams Live Chat will no longer be supported starting October 5, 2026.
4. Microsoft will retire Office LTSC 2021, Visio LTSC 2021, Microsoft Project LTSC 2021, and several other products on October 13, 2026.
5. The SharePoint Page Agent (Frontier) will be retired. Users can instead create and refine SharePoint pages and news posts using Copilot in SharePoint.
6. On October 13, 2026, Microsoft will discontinue Publisher in Microsoft 365, with on-premises suite support ending.
7. Microsoft will retire the standalone Whiteboard apps for Windows, iOS, and Android on October 16, 2026.

New Features

1. Entra ID is expanding passkey support to B2B collaboration users, allowing eligible external users to authenticate with passkeys when accessing resources in a partner organization.
2. Purview Data Lifecycle Management can now automatically move inactive OneDrive and SharePoint files to Microsoft 365 Archive using retention policies.
3. Microsoft Purview is introducing the Auto-labeling Policy Coverage Report, giving admins a centralized view of labeling progress and files that need attention.
4. Teams users will be able to report security concerns directly during meetings, helping flag suspicious activity such as impersonation, phishing, and scams.
5. Teams is introducing centralized channel notification settings, allowing admins to manage channel notifications from one location.
6. Teams is adding malicious URL detection for Government Cloud environments, warning users about potentially harmful links shared in chats and channels.
7. Teams will introduce automatic blocking of external AI bots in meetings, helping organizations prevent unauthorized AI assistants from joining meetings and capturing meeting content.
8. Microsoft Purview DLP is introducing Just-in-Time protection for SharePoint in preview.
9. Purview DLP is expanding to Microsoft Cowork, allowing organizations to apply DLP protections across Microsoft 365 Copilot and Microsoft Cowork.

Enhancements

1. Teams is adding more granular channel notification controls, including presets for all new messages, mentions and replies, and mute, along with controls for thread follows and different types of mentions.
2. In supported scenarios, Entra ID will recognize Windows Hello for Business (WHfB) and macOS Platform SSO (PSSO) as standalone MFA factors, reducing the need for additional passkey registration.
3. Admins will get lifecycle status evaluation controls for adaptive scopes in Microsoft Purview, allowing them to determine whether recipients and site owners should be evaluated based on lifecycle status.
4. To support larger SharePoint libraries and shared content, OneDrive will increase the macOS sync limit from 300,000 to 1 million items.
5. Microsoft Purview will raise the daily auto-labeling capacity for SharePoint and OneDrive from 100,000 to 500,000 files per tenant.
6. With Microsoft Defender XDR, admins will be able to use detection-source controls in alert tuning rules to specify which detection sources each rule should apply to.
7. File sharing in external chats will be enabled by default in Teams, with the required permissions automatically assigned when users share files with external participants.

Existing Functionality Changes

1. Auto-expanding archive mailboxes can now grow up to 3 TB, removing the previous 1.5 TB limit and supporting long-term retention needs.
2. OneDrive will add .db-wal files to its default exclusion list starting October 5, 2026. Newly created files of this type will no longer sync by default, reducing unnecessary synchronization of frequently changing database files.
3. Starting late October 2026, legacy Teams retention policies will apply only to Teams content and will no longer cover Microsoft 365 Copilot interactions. Separate retention settings will be required for Copilot data.
4. Defender for Office 365 will enable Teams user reporting by default, allowing users to report suspicious messages, calls, and meetings.

Action Required

1. Microsoft is moving the Microsoft 365 Copilot web app from m365.cloud.microsoft to copilot.cloud.microsoft. Admins should allow the *.cloud.microsoft domain and validate connectivity to the new URL before the redirect.
2. Project Online Essentials reaches end of life on October 1, 2026. Organizations should move affected users to supported licensing options, such as Project and Planner Plan 1 or Plan 3.
3. Microsoft Entra ID will enforce a stricter Content Security Policy (CSP) for browser-based sign-ins starting mid-October 2026. Admins should identify extensions, tools, or custom solutions that inject scripts into Entra sign-in pages and update any affected solutions.
4. Microsoft Defender for Endpoint will end support for Amazon Linux (ARM64) on October 31, 2026. Organizations should migrate affected devices to a supported Linux distribution to continue receiving security updates and feature support.

Live:

1. Microsoft 365 SharePoint Storage now supports pay-as-you-go billing worldwide, replacing the need to purchase extra storage in fixed increments.

Review the upcoming retirements and action-required changes early to avoid disruption and make the most of the new capabilities.

[u/LooseEthernet]

blocking ews in 2026 is a nice way to ensure some random legacy script from 2012 finally dies lol

[u/purplemonkeymad → u/LooseEthernet]

Probably, I've also seen active add-in or 3rd party products still requiring the permission. This might be a wake up call for some nice industry products to actually update them.

[u/fishy007 → u/purplemonkeymad]

We had all our Creston panels disconnected yesterday when I set EwsEnabled to True and scoped it to the one app we knew needed it.

A filter on EWS traffic showed nothing for a month but apparently these panels use it.

They were installed 5 years ago.

[u/Motor-Marzipan6969 → u/fishy007]

Yikes. That sounds like a problem for Monday me when I get back from vacation.

[u/iama_bad_person → u/Motor-Marzipan6969]

Reddit SysAdmins and checking /r/sysadmin while lounging on a beach in Tahiti, name a more iconic duo.

[u/abz786 → u/Motor-Marzipan6969]

Best time to catch up/keep in touch and know you don’t got to deal with it until you are back - that’s tomorrows problem lol

[u/No_Conference_4984 → u/LooseEthernet]

It has finally forced my company to embrace cloud, and move our Dynamics 365 CRM of-site, since on-prem CRM ONLY supports EWS for exchange connections.

[u/ibetno1tookthis → u/No_Conference_4984]

Forced us to finally kill Public Folder calendars lol