Microsoft Outlookの戦略的方向性について、TechRepublic公式の報道記事（https://www.techrepublic.com/article/news-microsoft-extends-classic-outlook-retirement-deadline/）で確認できます。Existing References describe what Outlook is, its Exchange Online-based enterprise-management differentiator vs. Gmail, and Copilot-assisted daily use cases; none discuss the classic-to-new-Outlook retirement timeline, so this is new.具体的には「"The current extension moves the classic client's retirement date to at least April 2027, allowing users sufficient time to plan and migrate." "Classic Outlook will still be supported for organizations and customers with perpetual licenses (such as Office LTSC) at least through 2029." "The revised date aligns with the start of Microsoft's 'Opt-out' phase (originally scheduled for April 2026), where the New Outlook will become the default experience."」といった記載が確認できます。限界として、これは当該Source公表時点の方針表明であり、その後変更される可能性があります。 Microsoft's migration timeline has already been revised at least once (originally April 2026 for opt-out, extended to April 2027 per this reporting), so these dates may be revised again before actual cutover; TechRepublic is reporting on Microsoft's announcement rather than being the primary policy source.Current Statusとして、2026年08月26日に当該Sourceを取得し、上記の内容を確認しました。Source種別としては、これは第三者であるTechRepublicによる報道であり、企業の自己申告とは性質が異なりますが、報道時点の取材内容に基づくものです。