| 仕様 | Users might get an error applying an encrypted sensitivity label when replying to an encrypted message sent from an external organization Outlook Known issues in February 2026 updates | 2026-02-13 |
| 調査中 | Can't use Reply All in email messages in Microsoft 365 groups Outlook Known issues in November 2025 updates | 2025-11-14 |
| 解決 | Microsoft Editor is not available in new Outlook for GCC tenants Outlook Known issues in October 2025 updates | 2025-10-10 |
| 回避策あり | Delay in sending email in New Outlook for Windows Outlook Known issues in September 2025 updates | 2025-09-18 |
| 解決 | Outlook desktop alert notifications open behind other applications Outlook Known issues in September 2025 updates | 2025-09-04 |
| 解決 | Error, "You may need to make an app password," when you add an account or send/receive email from some third-party email accounts Outlook Known issues in June 2025 updates | 2025-06-18 |
| 調査中 | Error when trying to print a Word document attached to an email in new Outlook for Windows Outlook Known issues in May 2025 updates | 2025-05-22 |
| 解決 | Go back to classic Outlook button not working correctly in new Outlook Outlook Known issues in March 2025 updates | 2025-03-27 |
| 解決 | Unable to save updates in Mobile devices settings for new Outlook Outlook Known issues in February 2025 updates | 2025-02-18 |
| 解決 | Microsoft Editor proofing or spellcheck languages change unexpectedly in new Outlook for Windows Outlook Known issues in January 2025 updates | 2025-01-29 |
| 解決 | Hovering over a hyperlink in an email may not display embedded URL in a pop-up tooltip in new Outlook Outlook Known issues in December 2024 updates | 2024-12-17 |
| 回避策あり | New Outlook users unexpectedly see the "Welcome to Outlook 2016" setup wizard Outlook Known issues in September 2024 updates | 2024-09-19 |
| 解決 | Calendar preview appears blank for meetings received on behalf of another person in new Outlook Outlook Known issues in August 2026 updates | — |