{"id":14188,"date":"2025-12-09T06:01:08","date_gmt":"2025-12-08T21:01:08","guid":{"rendered":"https:\/\/m365jp.net\/?p=14188"},"modified":"2025-12-09T06:01:20","modified_gmt":"2025-12-08T21:01:20","slug":"servicerestored-ex1192586-exchange-online-some-users-may-be-unable-to-open-inbound-secure-multipurpose-internet-mail-extensions-s-mime-encrypted-email-messages","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2025-12-09-servicerestored-ex1192586-exchange-online-some-users-may-be-unable-to-open-inbound-secure-multipurpose-internet-mail-extensions-s-mime-encrypted-email-messages","title":{"rendered":"[serviceRestored] EX1192586 | Exchange Online | Some users may be unable to open inbound Secure\/Multipurpose Internet Mail Extensions (S\/MIME) encrypted email messages"},"content":{"rendered":"
\n
\n
\n\n\n\n
EX1192586 | Exchange Online | Some users may be unable to open inbound Secure\/Multipurpose Internet Mail Extensions (S\/MIME) encrypted email messages<\/th>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n\n\n\n\n\n\n\n\n\n\n
Status<\/th>\nserviceRestored<\/td>\n<\/tr>\n
Classification<\/th>\nincident<\/td>\n<\/tr>\n
User Impact<\/th>\nUsers may have been unable to open some inbound S\/MIME encrypted email messages in Exchange Online.<\/td>\n<\/tr>\n
Last Updated<\/th>\n12\/08\/2025 20:47:46<\/td>\n<\/tr>\n
Start Time<\/th>\n11\/30\/2025 00:00:00<\/td>\n<\/tr>\n
End Time<\/th>\n12\/08\/2025 10:00:00<\/td>\n<\/tr>\n
Latest Message<\/th>\nTitle: Some users may be unable to open inbound Secure\/Multipurpose Internet Mail Extensions (S\/MIME) encrypted email messages<\/p>\n

User impact: Users may have been unable to open some inbound S\/MIME encrypted email messages in Exchange Online.<\/p>\n

More info: This issue affected users with the Dynamic Delivery policy enabled.
We previously disabled Dynamic Delivery “for S\/MIME messages” while we worked to resolve this issue, which has since been re-enabled.<\/p>\n

Final status: We’ve confirmed that the configuration has been updated and validated this action has remediated the impact using service telemetry.<\/p>\n

Scope of impact: Some users with Dynamic Delivery enabled that were attempting to open S\/MIME encrypted email messages may have been impacted.<\/p>\n

Start time: Sunday, November 30, 2025, at 12:00 AM UTC<\/p>\n

End time: Monday, December 8, 2025, at 10:00 AM UTC<\/p>\n

Root cause: A recent service update that intended to introduce a new Microsoft Defender for Office 365 feature incorrectly marked S\/MIME messages for delivery, resulting in impact.<\/p>\n

Next steps:
– We’re continuing our analysis of the impacting configuration change to better identify and prevent similar issues in the future.<\/p>\n

This is the final update for the event.<\/td>\n<\/tr>\n

Machine Translation<\/th>\n\u30bf\u30a4\u30c8\u30eb:\u4e00\u90e8\u306e\u30e6\u30fc\u30b6\u30fc\u306f\u3001\u53d7\u4fe1\u3059\u308bSecure\/Multipurpose Internet Mail Extensions(S\/MIME)\u6697\u53f7\u5316\u30e1\u30fc\u30eb\u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u958b\u3051\u3089\u308c\u306a\u3044\u5834\u5408\u304c\u3042\u308a\u307e\u3059<\/p>\n

\u30e6\u30fc\u30b6\u30fc\u3078\u306e\u5f71\u97ff:\u30e6\u30fc\u30b6\u30fc\u306fExchange Online\u3067\u4e00\u90e8\u306e\u53d7\u4fe1S\/MIME\u6697\u53f7\u5316\u30e1\u30fc\u30eb\u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u958b\u3051\u306a\u304b\u3063\u305f\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n

\u8a73\u7d30\u60c5\u5831:\u3053\u306e\u554f\u984c\u306f\u52d5\u7684\u914d\u9001\u30dd\u30ea\u30b7\u30fc\u3092\u6709\u52b9\u306b\u3057\u305f\u30e6\u30fc\u30b6\u30fc\u306b\u5f71\u97ff\u3057\u307e\u3057\u305f\u3002
\u4ee5\u524d\u306f\u3053\u306e\u554f\u984c\u306e\u89e3\u6c7a\u4f5c\u696d\u4e2d\u306b\u300cS\/MIME\u30e1\u30c3\u30bb\u30fc\u30b8\u7528\u300d\u306e\u52d5\u7684\u914d\u4fe1\u3092\u7121\u52b9\u306b\u3057\u3066\u3044\u307e\u3057\u305f\u304c\u3001\u73fe\u5728\u518d\u3073\u6709\u52b9\u5316\u3055\u308c\u307e\u3057\u305f\u3002<\/p>\n

\u6700\u7d42\u72b6\u6cc1:\u8a2d\u5b9a\u304c\u66f4\u65b0\u3055\u308c\u3001\u30b5\u30fc\u30d3\u30b9\u30c6\u30ec\u30e1\u30c8\u30ea\u3092\u7528\u3044\u3066\u5f71\u97ff\u304c\u89e3\u6c7a\u3057\u305f\u3053\u3068\u3092\u78ba\u8a8d\u3057\u307e\u3057\u305f\u3002<\/p>\n

\u5f71\u97ff\u7bc4\u56f2:\u52d5\u7684\u914d\u4fe1\u304c\u6709\u52b9\u3067S\/MIME\u6697\u53f7\u5316\u30e1\u30fc\u30eb\u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u958b\u3053\u3046\u3068\u3057\u305f\u4e00\u90e8\u306e\u30e6\u30fc\u30b6\u30fc\u306f\u5f71\u97ff\u3092\u53d7\u3051\u305f\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n

\u958b\u59cb\u6642\u9593:2025\u5e7411\u670830\u65e5(\u65e5)0:00 UTC<\/p>\n

\u7d42\u4e86\u6642\u523b:2025\u5e7412\u67088\u65e5(\u6708)\u5348\u524d10\u6642(UTC)<\/p>\n

\u6839\u672c\u539f\u56e0:\u6700\u8fd1\u306e\u30b5\u30fc\u30d3\u30b9\u30a2\u30c3\u30d7\u30c7\u30fc\u30c8\u3067\u3001Office 365\u7528\u306e\u65b0\u3057\u3044Microsoft Defender for 365\u6a5f\u80fd\u3092\u5c0e\u5165\u3057\u3088\u3046\u3068\u3057\u305f\u969b\u306b\u3001S\/MIME\u30e1\u30c3\u30bb\u30fc\u30b8\u304c\u8aa4\u3063\u3066\u914d\u4fe1\u5bfe\u8c61\u3068\u3057\u3066\u30de\u30fc\u30af\u3055\u308c\u3001\u5f71\u97ff\u304c\u751f\u3058\u307e\u3057\u305f\u3002<\/p>\n

\u6b21\u306e\u30b9\u30c6\u30c3\u30d7:
– \u4eca\u5f8c\u3082\u540c\u69d8\u306e\u554f\u984c\u3092\u3088\u308a\u6b63\u78ba\u306b\u7279\u5b9a\u3057\u9632\u6b62\u3059\u308b\u305f\u3081\u3001\u5f71\u97ff\u3092\u53d7\u3051\u305f\u69cb\u6210\u5909\u66f4\u306e\u5206\u6790\u3092\u7d99\u7d9a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n

\u3053\u308c\u304c\u30a4\u30d9\u30f3\u30c8\u306e\u6700\u7d42\u30a2\u30c3\u30d7\u30c7\u30fc\u30c8\u3067\u3059\u3002<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

EX1192586 | Exchange Online | Some users may be unable to open inbound Secure\/Multipurpose Internet Mail Exten […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-14188","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/14188","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/comments?post=14188"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/14188\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=14188"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=14188"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=14188"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}