Mac mail Classic Layout on Big Sur

MooneyTed wrote:

In the course of migrating to a new computer with Big Sur, my Mac Mail remained in the much loved Classic layout that I've used for decades. Obviously Classic layout can & does work with Big Sur because it's been just fine, and just like always.

But when adding a new user on the machine, they get the new layout which just will not let us do the handy second-nature things we've all come to rely on over the years. So the question is: I know Classic will run on Big Sur because it is doing so ... so is there any Apple-approved way to do it?

Make a change—

Mail>View>Use Column layout

Mail User Guide for Mac - Apple Support

To clarify, the Column Layout (Classic View) is not the default view. Your view settings were carried over during the upgrade but a new user receives the new view by default. You merely need to turn on Column View and make other view or preference changes, etc. for a new user.