Hi @Loh, Wai Mun
Welcome to our forum!
I want to check if any member in this forum knows how to set this or if it is by design similar to the web outlook, where double-clicking (opening a new window) will not mark an email as red.
Yes, in my test environment I had the same results as you. According to my tests, when you double-click on a message in New Outlook, it will open the message in a new window, but it will still be unread.
Please kindly understand that many functions are not designed at present. And there are some differences between the new version and the classic version. It is recommended that you could post the functions you expect and your sincere suggestions on the website dedicated to collecting feedback. We sincerely welcome your suggestions, and thanks for your understanding and support!
Hope this helps!
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