If your team relies on secure communications, you can’t ignore the newly uncovered encrypted email bug in classic Outlook. A recent Microsoft security update to improve protection has unintentionally disrupted how users open encrypted emails. While Microsoft is working on a fix, the issue has already confused businesses that depend on email encryption to protect sensitive information.
Why You Need To Pay Attention to This Microsoft Bug
Encrypted emails aren't just nice-to-haves. They're often required for compliance, to protect trade secrets, or to maintain client trust.
When the Outlook app breaks email decryption like this, it creates real headaches: delayed responses, missed opportunities, and potential security risks if people start looking for workarounds outside of official channels. The bug doesn't hit everyone, but if your team sends or receives "Encrypt Only" messages regularly, you're probably already facing confusion.
What Triggered the Issue in Classic Outlook?
Microsoft posted an update on January 6, 2026, to explain the issue. They confirmed that the problem began after users installed Current Channel Version 2511 (Build 19426.20218). After updating, some recipients found they could no longer open “Encrypt Only” messages in classic Outlook. Instead, they received a message requesting that they verify their credentials.
Even after clicking to open the message and entering credentials, the email often appears as an unreadable attachment, such as message_v2.rpmsg, rather than the actual content. Unfortunately, opening the message doesn’t always solve the problem, because the issue is tied to how Outlook handles email decryption after the recent security update, not user credentials or permissions.
For organizations that exchange contracts, financial data, or internal credentials by email, this disruption can slow down daily operations.
Microsoft’s Response
Microsoft confirms that it’s actively working on a permanent fix, and emphasizes that the problem is limited to classic Outlook and specific encryption settings. They also provided temporary workarounds so businesses can continue accessing encrypted emails bug is resolved.
To access secure messages:
- Open encrypted emails outside the Reading Pane, such as in a new window.
- Access the message through Outlook on the web, where encryption continues to work.
- Ask the sender to resend the email using a different encryption method, if appropriate.
To send encrypted emails without problems, users have two options. They can go back to an Outlook version from before the issue started (build 19426.20186 is the prior build that still works) and then send the email. They can also encrypt the message using the option on the Options ribbon, rather than the File > Encrypt option.
These steps aren’t ideal, but they can keep workflows moving while the fix is in development. Microsoft has stated that a correction is coming, so continue monitoring updates and using the workarounds when possible to minimize disruption and maintain secure communications.
The encrypted email bug in classic Outlook is annoying and inconvenient, but you can work around it and keep your email messages secure while Microsoft works on a solution. Your best option is to be proactive and keep up with the recommended action. You'll keep emails secure and communication running smoothly without glitchy roadblocks.
