How can I select to see message size column in New Outlook

@Lester Kalms said

how to add columns in the New Outlook ... Windows

You can't.

All you can do at this point is Vote for and Comment on this Feature Request and hope that someone from Microsoft adds it to their Roadmap for New Outlook for Windows.

(You must "Sign In" at the top right of the Feedback page before you can vote).

Please add back the ability to add columns to inbox
https://feedbackportal.microsoft.com/feedback/idea/8935287a-4762-f011-95f2-7c1e52a55eeb

Or if that doesn't fit your requirements, create a new Request at
https://feedbackportal.microsoft.com/feedback/post
(Please put a link to your Request in a new Comment here, so the rest of us can Vote for it)

Hi Lester,

I greatly appreciate you sharing your experience, and I truly understand your concern.

As of now, only Classic Outlook supports adding and removing columns when using a list view. New Outlook for Windows doesn’t support adding or customizing message-list columns such as Size settings. Its currently available message-list settings include mainly sender/subject order, density, conversation organization, preview text, and Reading Pane layout.

I understand this isn’t the outcome you were hoping for. As a forum user, I don’t have visibility into internal design/structure or the ability to modify how the product behaves. I can only help test and confirm how the feature behaves and ensure you have clear information.

If you see this feature should be improved or this is affecting your workflow, I strongly recommend submitting your feedback through the Outlook · Community. The product development team doesn't actively monitor this forum, so this is the most effective way to ensure your voice reaches the product team and can be considered for future improvements.

Once you've submitted your feedback, feel free to share the link here in the comments. I’ll be happy to upvote it to help bring more visibility.

Additionally, as other users have raised similar concerns and may not be aware of where to share their feedback, I hope this response helps clarify the situation and suggests a potential next step. Highlighting this information can make it more visible to others in the community who may be facing the same issue, making it easier for them to find guidance and contribute their feedback as well. 

Thank you again for your time and for raising this important usability concern. 

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