Use Classic Outlook? This Microsoft bug might stop you from opening encrypted emails

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A phone sitting on a laptop keyboard with the Microsoft Outlook logo on the screen.
(Image credit: Shutterstock / JarTee)
  • Outlook patch (Build 19426.20218) broke “Encrypt Only” emails, showing unreadable attachments
  • Workarounds: use Options ribbon encryption or revert to Build 19426.20186 via Command Prompt
  • Microsoft also disabled inline SVGs in Outlook for Web and new Outlook for Windows

Microsoft released a new patch for classic Outlook, and broke how encrypted emails work. It is currently working on a fix, and in the meantime, it offered a few ways to open encrypted emails in the popular client app.

In a short update posted on January 6, Microsoft said that after updating to Current Channel Version 2511 (Build 19426.20218), email recipients may not be able to open “Encrypt Only” messages.

The error manifests in the Reading Pane, where users might get a message saying "This message with restricted permission cannot be viewed in the reading pane until you verify your credentials. Open the item to read its contents and verify your credentials."

Two workarounds

After opening the email, users will find an attachment message_v2.rpmsg and won’t be able to read the contents.

The problem happens for users who encrypt the email using the settings under the email File dialog (File > Encrypt), Microsoft further explained. To prevent the issue, there are two possible workarounds. For the first one, users should select the Options ribbon, then select Encrypt, and choose Encrypt or Do Not Forward.

The second workaround is to revert to a build before the issue started and then send the email. The issue started with build 19426.20218, and the next prior build that works is 19426.20186. To revert Office, users should open an elevated Command Prompt, and run this command:

"%programfiles%\Common Files\Microsoft Shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.19426.20186

Email is by far the most attacked vector, and the go-to communications platform for initial compromise. Microsoft often patches Outlook to close different holes and has, only recently, changed how Outlook handles SVG images.

In a Microsoft 365 Message Center update, the tech giant said, "Inline SVG images will no longer be displayed in Outlook for Web or the new Outlook for Windows. Instead, users will see blank spaces where these images would have appeared."

Via BleepingComputer

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Sead Fadilpašić

Sead is a seasoned freelance journalist based in Sarajevo, Bosnia and Herzegovina. He writes about IT (cloud, IoT, 5G, VPN) and cybersecurity (ransomware, data breaches, laws and regulations). In his career, spanning more than a decade, he’s written for numerous media outlets, including Al Jazeera Balkans. He’s also held several modules on content writing for Represent Communications.

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