Microsoft has confirmed a new issue affecting encrypted emails in classic Outlook, the company’s older email client that continues to coexist alongside the newer Outlook experience. According to an official Microsoft support page, users running the latest classic Outlook version 2511 may find themselves unable to open encrypted emails, even after successfully verifying their identity. The problem appears to affect email decryption rather than authentication itself, leaving affected messages inaccessible once opened.
At the moment, Microsoft says the root cause of the bug is still unknown. The company has acknowledged the issue publicly and stated that it is actively investigating, with plans to update the support documentation as soon as more details become available. There is no indication yet of how widespread the problem is or whether it impacts all encryption scenarios equally.
Until a permanent fix is released, Microsoft has outlined a couple of temporary workarounds for impacted users. One option is to roll back to an older version of the classic Outlook client, which reportedly does not exhibit the same decryption issue. Another workaround involves changing how email encryption is applied: instead of encrypting messages through the File menu, users are advised to apply encryption using the Options tab when composing emails.
This latest hiccup adds to the growing list of issues users have encountered with classic Outlook in recent months, particularly around security and feature parity with the new Outlook experience. For organizations that rely heavily on encrypted email for sensitive communications, the bug could be disruptive until Microsoft delivers a proper fix.
