Hello Millsy5,
Thanks for your post in this community.
Regarding your post, would like to reconfirm does your concern is with Outlook desktop app or Outlook web app? However based on your post question category, seems your concern is with Outlook for Windows app, so based on it we have checked from our end and seems when we double click on any emails, it will open in separate Window but again to view all, as you said with the Windows Shortcut key (Alt+Tab) we can view it in smaller view only. Besides this, at this moment there is no such option. We do understand your requirement and appreciate your suggestion but as this is related with Outlook product’s feature, so recommend to kindly submit your valubale feedback to Outlook product development team via go to Help > Feedback. This is the quickest route to get your suggestion to our developers’ ears. At this point, your kind co-operation will be highly appreciated.
Thank you so much for your kind understanding and have a nice day. Be safe with good health.
Regards,
Ankita Vaidya