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Classic Outlook encrypted-email opening bug after update

Service Disruption
First reported
Last updated
Happening score
H score 1
1 unique sources, 2 articles

Summary

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Microsoft is investigating a classic Outlook disruption that prevents some users from opening Encrypt Only encrypted emails after Current Channel Version 2511 (Build 19426.20218). Affected messages can appear as a message_v2.rpmsg attachment or show a reading-pane credential error, leaving the content inaccessible. Microsoft says a fix is in progress and provides temporary workarounds, including saving encrypted mail before sending or rolling back to 16.0.19426.20186.

Related Happenings

Microsoft Exchange Online mail flow disruption

Service Disruption
H score25 First: 02.06.2026 20:02 Last: 02.06.2026 20:02 Sources 1

About this happening: Microsoft is addressing a **widespread Exchange Online service disruption** that is delaying and failing email delivery for customers across **North America** and **Germany**. The...

Open Happening

Microsoft Exchange Server spoofing/XSS flaw under active exploitation (CVE-2026-42897)

Vulnerability
H score37 First: 15.05.2026 09:19 Last: 15.05.2026 09:19 Sources 1

About this happening: **CVE-2026-42897** is an **actively exploited** **spoofing** vulnerability in **on-premises Microsoft Exchange Server** that can lead to **arbitrary JavaScript execution** in a br...

Latest development: 09.06.2026 20:57

Microsoft identifies CVE-2026-42897 in Microsoft Exchange Server as an actively exploited spoofing vulnerability that can lead to JavaScript execution in a target’s browser when a specially crafted email is opened in Outlook Web Access under certain interaction conditions. Microsoft says mitigations are being pushed through the Exchange Emergency Mitigation Service while it continues work on the full update.

Open Happening

Microsoft Exchange Online blocks legacy TLS for POP3 and IMAP4 starting July 2026

Security Tool/Service
H score11 First: 28.04.2026 16:18 Last: 28.04.2026 16:18 Sources 1

About this happening: **Microsoft** will block **TLS 1.0** and **TLS 1.1** for **POP3/IMAP4** access to **Exchange Online** in **July 2026**, which could break legacy mail clients and embedded devices...

Open Happening

Microsoft Classic Outlook email sending disruption

Service Disruption
H score0 First: 02.04.2026 12:12 Last: 02.04.2026 12:12 Sources 1

About this happening: **Microsoft** is investigating a **Classic Outlook** disruption that can prevent some users from sending or replying to email through **Outlook.com**, causing **NDR errors** and m...

Latest development: 06.04.2026 22:19

Microsoft fixed a known issue affecting some Classic Outlook users sending emails via Outlook.com that could return non-delivery reports (NDRs) with 0x80070005-0x0004dc-0x000524 errors. Microsoft said the service change was in production as of April 3, 2026, and advised affected users to use the New Outlook client or Outlook.com on the web; Microsoft also pointed users to downloading the Outlook Address Book for affected Outlook.com accounts.

Open Happening

Microsoft classic Outlook Gmail and Yahoo sync disruption

Service Disruption
H score0 First: 24.03.2026 17:12 Last: 24.03.2026 17:12 Sources 1

About this happening: The **classic Outlook** synchronization failure affecting **Gmail** and **Yahoo** accounts has been fixed, restoring email access for impacted users. Microsoft said the bug produc...

Open Happening

Timeline

  1. 30.01.2026 16:48 1 articles · 5mo ago

    Microsoft rolls out fix for classic Outlook encrypted-email bug

    Mitigation Patch Update

    Microsoft says a fix for classic Outlook is now available for Microsoft 365 customers in the Beta Channel after a December update broke access to encrypted emails sent with "Encrypt Only" permissions. The fix will roll out to the Current Channel and Current Channel Preview in February, and users who cannot upgrade yet can use the Encrypt option under the Options ribbon or roll back Outlook with officec2rclient.exe to 16.0.19426.20186.

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  2. 07.01.2026 18:30 2 articles · 6mo ago

    Microsoft investigates classic Outlook encrypted-email opening bug

    Initial Disclosure

    Microsoft investigates a classic Outlook known issue that prevents recipients on Current Channel Version 2511 (Build 19426.20218) from opening emails encrypted with "Encrypt Only" permissions, with some users seeing a message_v2.rpmsg attachment or a restricted-permission Reading Pane error instead of message content. Microsoft says the Outlook Team is working on a fix and provides temporary workarounds, including saving encrypted emails after encryption and before sending or rolling back to 16.0.19426.20186.

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