If I delete an email from my INBOX, I would like to have it go into my TRASH folder instead of being deleted immediately. I don’t see a setting for that. Surely I am missing it somewhere?
There is no such an option, Pushing “DEL” key should move your email to trash, “Shift + del” will always delete them.
Have you checked if you have more than one “trash” folder? Junk/trash for example.