Unable to Open .eml/.msg Files Using "Open in App" from SharePoint or OneDrive

[AmitaiBitonHarmonie]

Steps to reproduce

When attempting to open .eml or .msg files from SharePoint or OneDrive using the "Open in App" option, the action fails, resulting in unexpected behavior. Instead of opening the file in a compatible mail application (like Outlook), either:

• A file explorer window appears for a minute, followed by an error message.

• The file opens in Notepad, displaying binary data or unreadable characters.

This issue affects the ability to seamlessly open email files directly from SharePoint or OneDrive, resulting in a poor user experience.

Steps to Reproduce:

1. Upload an .eml or .msg file to any location on SharePoint or OneDrive.

2. Right-click the file and select "Open in App" from the context menu.

Observe the behavior:

• File explorer may open and eventually lead to an error message.
• Alternatively, Notepad may open with strange or unreadable content.
  Screenshots:

Expected behavior

The .eml/.msg file should open in the associated email application (such as Outlook), allowing the user to view the email content.

Actual behavior

A file explorer window opens and after a minute, an error message is displayed.

• In some cases, the file opens in Notepad with unreadable content, which is not the expected behavior for email files.

Error details

No response

[microsoft-github-policy-service]

Hi AmitaiBitonHarmonie! Thank you for bringing this issue to our attention. We will investigate and if we require further information we will reach out in one business day. Please use this link to escalate if you don't get replies.

Best regards, Teams Platform

[Meghana-MSFT]

We are mainly responsible for Microsoft Teams app development related issues. Based on the description your issue does not seem related to Teams app dev.

For general questions about Microsoft 365 and Office, please post your question on Microsoft 365 and Office
Community.