Using Classic Outlook on Windows for personal email, calendar, and contact management
Dear Nhan N. Nguyen,
Good day!
Thank you for posting to Microsoft Community. We are happy to assist you.
According to your description, the issue of your concern that the feature for drag and drop does not work on new Outlook.
Based on my tests, it is a fact that this feature is not available when downloading the attachments. (uploading is OK.)
We truly understand how frustrating it is, at this moment, please toggle off the New Outlook as a workaround.
In addition, please be kindly to share your using experience and suggest this as a new feature to the New Outlook's engineering team as below:
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Microsoft Community Moderator.