Dear marvinruddell,
Good day! Thank you for posting to Microsoft Community.
Spell check in the new Outlook locate under Editor feature. Kindly set your ribbon on classic and create new email, click New email--> Message tab-->click on Editor -->Editor Settings--> select your language preference and enable spelling and grammar check -->OK.

However, if Editor is grayed out in your new outlook, please kindly go to Settings (The gear icon at the right top corner) -->General -->Privacy and data -->Privacy settings -->toggle on button for "Turn on experiences that analyze your content" -->OK.


I look forward to your update. Please feel free to let me know how it goes or if I got you wrong. If you still have any concerns, please let me know so I can provide more suggestions.
Thank you for your precious time. Have a nice day.
Sincerely,
Libeamlak | Microsoft Community Moderator