Exchange Web Services APIを廃止するのでGraphへの移行が推奨されていましたが、2026年の10月からEWSに対する非MSアプリからのAPIリクエストを全部ブロックするという発表です。
EWS及びJavaと.NETのEWS SDKSに対するセキュリティアップデートだったりその他の軽微なアップデート自体は続ける予定で、プロダクトデザインと機能も変更はしない予定で、まだ普通にEWSの使用はサポートされていますが、Microsoft Graph経由でのExchange Onlineへのアクセスを強く推奨するとのことです。
また、今回のアナウンスはMicrosoft 365とExchange Onlineのみが対象で、Exchange ServerのExchange Web Servicesに関しては対象外です。また、Exchange Onlineの変更はWindows/Mac版Outlook、Teams及び他のMS製品には影響を及ぼさないはずとのことです。
他の長い部分に関しては、GraphとEWS APIの違いだったりMSのライフサイクルポリシーの説明等なので、別に読まないでも大丈夫です。
ただ、いくつかの機能の差（the gaps）が上げられているので最後にそこだけ上げておきます。
また、「その機能差は埋めていきたいけどもしかすると無理なのもあるかもしれない」、と正直に言っています。
～～～
・アーカイブメールボックスへのアクセス – Microsoft Graph経由でアーカイブ済みメールボックスへアクセスするために取り組んでいるので、今後数ヶ月の間に関連の作業スケジュールを提供する予定。
・フォルダー関連情報/ユーザー設定 – これらの機能については現在調査中であり、今後数カ月以内に最新のスケジュールを知らせる。
・Exchange Online Management – 現在、この機能に関するソリューションを調査中。
・パブリックフォルダーへのアクセス – Graph API を介してのExchange Online パブリックフォルダーへのサードパーティアプリ ケーションアクセスを提供する必要性を検討中なので、現在EWS APIで、バックアップとリストア以外で、パブリックフォルダーを使用するソリューションを構築している顧客やパートナーの意見を募集中。
We know there are several feature gaps between EWS and Microsoft Graph, and though the list below is not exhaustive, these are the gaps most frequently reported to us by developers:
- Access to Archive Mailboxes – We are working on delivering access to archive mailboxes via Microsoft Graph and will provide an updated timeline in the coming months.
- Folder Associated Information / User Configuration – We are working on these features and will provide an updated timeline in the coming months.
- Exchange Online Management – We are investigating solutions for this and will provide an updated timeline in the coming months.
- Access to Public Folders – We are reviewing the need to provide third-party app access to Exchange Online public folders via the Graph API and are interested in hearing from customers and partners who build solutions that use public folders, other than backup and restore solutions. If you are willing to share details on how you use EWS with public folders, we’d love to hear from you, and you can reach us at EWSandPFfeedback@microsoft.com.
We know there are other gaps not listed above, and we continue to work on closing them, but it’s possible some functionality will not make it to Microsoft Graph.
～～～
まだGraphが整備されていないし急いでなにかをしなくとも一応大丈夫だけど、意識はしておいたほうが良いですね。
原文
メッセージの概要
In 2018, we announced that we were no longer making feature updates to Exchange Web Services (EWS) in Exchange Online, and we advised developers to move to Microsoft Graph.
Today, we are announcing that on October 1, 2026, we will start blocking EWS requests from non-Microsoft apps to Exchange Online.
When this will happen:
October 1, 2026
How this affects your organization:
While the EWS components of the service will continue to receive security updates and certain non-security updates, product design and features will remain unchanged. This change also applies to the EWS SDKs for Java and .NET, as well.
Despite this announcement, EWS is still available and supported for use in production environments. But we strongly suggest migrating to Microsoft Graph to access Exchange Online data and gain access to the latest features and functionality.
Today’s announcement and the retirement of EWS apply only to Microsoft 365 and Exchange Online (all environments); there are no changes to EWS in Exchange Server. Further, the changes in Exchange Online do not affect Outlook for Windows or Mac, Teams, or any other Microsoft product.
Migrating Applications to Microsoft Graph
We know there are several feature gaps between EWS and Microsoft Graph, and though the list below is not exhaustive, these are the gaps most frequently reported to us by developers:
- Access to Archive Mailboxes – We are working on delivering access to archive mailboxes via Microsoft Graph and will provide an updated timeline in the coming months.
- Folder Associated Information / User Configuration – We are working on these features and will provide an updated timeline in the coming months.
- Exchange Online Management – We are investigating solutions for this and will provide an updated timeline in the coming months.
- Access to Public Folders – We are reviewing the need to provide third-party app access to Exchange Online public folders via the Graph API and are interested in hearing from customers and partners who build solutions that use public folders, other than backup and restore solutions. If you are willing to share details on how you use EWS with public folders, we’d love to hear from you, and you can reach us at EWSandPFfeedback@microsoft.com.
We know there are other gaps not listed above, and we continue to work on closing them, but it’s possible some functionality will not make it to Microsoft Graph. We encourage you to provide feedback to us, keep a close eye on the What’s new in Microsoft Graph page, and explore alternatives for functionality or features not available in Microsoft Graph.
Next Steps
The retirement of these APIs follows our Modern Lifecycle Policy. We understand changes like this may cause some inconvenience, but we are confident it will ensure more secure, reliable, and performant experiences.
We will publish regular communications as we progress towards this deadline to aid affected tenants in identifying EWS usage. We encourage all customers to monitor Message Center and this blog for related content.
Thank you in advance for updating and opening your apps to a wider range of useful and intelligent features on Microsoft Graph. We are extremely excited about the growing opportunities that Microsoft Graph offers to developers, and we remain fully committed to our journey to empower developers to access Microsoft 365 data with the most modern features and tools.
