Issue with opening encrypted email

Question

Issue with opening encrypted email

MoazW 0

I'm having trouble opening encrypted emails in Outlook (web, desktop, and mobile apps). The first email opened automatically with a .rpmsg attachment. Subsequent email from the same sender had a SecureMessageAtt.html attachment with a prompt saying "This is a secure message. To read it, open the attachment."

After opening it, I was asked to set a new password, which led to a secure webpage with the message.rpmsg attachment.

Clicking "Read the message" button on this webpage redirected me to the same email in web Outlook with the SecureMessageAtt.html and the cycle repeats. After that, I have not been able to open any of the encrypted emails from this sender. I've tried multiple devices, but the issue persists. Any help would be appreciated!

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Answer 1

Joan Hua-MSFT 5,300 Microsoft External Staff

Hi @MoazW

Welcome to our forum！

What is your account? Microsoft 365 or outlook.com or something else?

Does the issue occur recently on Outlook Desktop Client? Do you have any specific operation before the issue occurred?

What is the version of your Outlook? It is recommended that you please check the Outlook client version (File>Office Account>Product Information) and try to upgrade to the latest version to see if the problem is resolved.

How did the emails be encrypted? By Microsoft Purview Message Encryption or S/MIME or something else?

If the emails were encrypted by Microsoft Purview Message Encryption, you may refer to the article and have a try step-by-step.

User's image

In addition, you may try to review the messages in a new window in New Outlook to see if the issue persists. More information: View and reply to encrypted messages in Outlook for Windows - Microsoft Support

If all above do not work, it is recommended that you contact the sender to check that if the password entered is correct and the attachment has been added successfully and validly.

Hope it helps!

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Joan Hua-MSFT 5,300 Reputation points Microsoft External Staff

2025-03-05T02:08:03.58+00:00

Hi @MoazW

Just checking in to see if above information was helpful. If it is useful, would you mind marking the helpful post as an answer? Which would benefit others who also has similar issues in forum. Warm thanks！
MoazW 0 Reputation points

2025-03-05T06:26:21.2833333+00:00

Hi @Joan Hua-MSFT

Thank you very much for your reply. I have a personal Outlook account, so I cannot run the diagnostic you suggested. I am not sure how the sender encrypted it, as it is from a bank. The first email from this sender decrypted by itself and opened as a normal email would. However, the subsequent emails did not. It happened recently on the desktop client. After that, I have tried to open the email on the webpage, the iOS Outlook app, and different laptops. I am using the latest Outlook version and opening the email in a new window does not help. Thanks!
Joan Hua-MSFT 5,300 Reputation points Microsoft External Staff

2025-03-07T05:42:42.3666667+00:00
Hi @MoazW

Thanks for response.

If the first email decrypted automatically, it’s likely that the encryption method is supported by your Outlook client. However, subsequent emails may have been encrypted differently or require additional steps.

If the issue persists, it’s possible that:

The sender’s encryption settings have changed.

The email was not sent correctly.

Please contact the bank’s support team and explain the issue. They may provide:

A new decryption key or certificate.

Instructions for accessing the email securely.

Hope it helps.

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Issue with opening encrypted email

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