Microsoft 365 Alert – Service Degradation – Exchange Online – Users’ email that’s signed but not encrypted may be unable to be opened in Outlook desktop client – RESOLVED
19/07/2024 09:05:00 AM
Microsoft Reference: EX820374
Issue Status: RESOLVED
Issue Description: Users’ email that’s signed but not encrypted may be unable to be opened in Outlook desktop client.
More info: This impacts messages that are signed but not encrypted using Secure/Multipurpose Internet Mail Extensions (S/MIME) for version 4.2427.0 of the iOS Outlook mobile app and version 4.2427.1 of the Android Outlook mobile app.
Users receive an error when opening the affected signed email messages in Outlook on the web, but the content of the message is still available. The error states “S/MIME isn’t supported in this view”.
Final Update: 22/07/2024 08:33:00 AM – Microsoft confirmed that the new version containing the fix has been released for the iOS Outlook mobile app, version 4.2427.1 They recommend users manually update their iOS Outlook mobile app to version 4.2427.1, and their Android Outlook mobile app to version 4.2427.2 to remediate impact.
Scope of impact: Any user with version 4.2427.0 of the iOS Outlook mobile app or version 4.2427.1 of the Android Outlook mobile app that attempts to send or receive a signed email message without S/MIME encryption may be impacted.
Root cause: A code issue in version 4.2427.0 of the iOS Outlook mobile app and version 4.2427.1 of the Android Outlook mobile app that’s preventing messages signed without S/MIME encryption from being opened in the Outlook desktop client.