... or users can just be given the option and decide for themselves.
Config settings like that are a way for lazy designers to avoid making hard decisions.
Joel Spolsky wrote about this over 10 years ago:
Every time you provide an option, you're asking the user to make a decision. That means they will have to think about something and decide about it. It's not necessarily a bad thing, but, in general, you should always try to minimize the number of decisions that people have to make.
and
"But wait!" you say. "It's important to have options for advanced users who want to tweak their environments!" In reality, it's not as important as you think. This reminds me of when I tried to switch to a Dvorak keyboard. The trouble was, I don't use one computer. I use all kinds of computers. I use other people's computers. I use three computers fairly regularly at home and three at work. I use computers in the test lab at work. The trouble with customizing your environment is that it just doesn't propagate, so it's not even worth the trouble.
http://www.joelonsoftware.com/uibook/chapters/fog0000000059....
like the 'designers' of gnome3 (using the term loosely here) who thinks focus-follow-mouse and click-does-not-raise-window are things that only the devil would use and so no one should be allowed 'for usability sake' and 'think of the children'
think about it. a black wallpaper is the best readability option. period. so let's remove the user ability to change wallpapers pronto!
what i say "everytime you provide the user an option, you are asking him to, if he uses the software enough, to take a little second to make a decision that will give him an incredible productivity edge"
now, stop being lazy and hiding behind excuses. work on the real problem: how to present the options so they are not in the way, like joel mentions it while not being missed by the user
This doesn't mean eliminate all choice. There are enough choices that users will have to make anyway: the way their document will look, the way their web site will behave, or anything else that is integral to the work that the user is doing. In these areas, go crazy: it's great to give people choices: by all means, the more the merrier. And there's another category of choice that people like: the ability to change the visual look of things, without really changing the behavior. Everybody loves WinAmp skins; everybody sets their desktop background to a picture. Since the choice affects the visual look without affecting the way anything functions, and since users are completely free to ignore the choice and get their work done anyway, this is a good use of options.
(Note this part: everybody sets their desktop background to a picture)
So you can only go crazy on futile options and not useful ones? Give me a break.
There are useful settings that help me accomplish the task, and then there are not so useful settings where developer simply couldn't decide. I particulary dislike configuration UIs that devote whole section of toggles and switches for configuring the configuration screen itself.
While I understand that users can be easily overwhelmed with a plethora of options, this one makes sense.. especially for an email app.
Rethink your UX, put together prototypes, user-test, and repeat. Leave configuration option as last resort. That's the approach for app that wants to "Simplify my life" and "Make me amazing".
If the back button did it's job properly then the feature would just work; you wouldn't need to manually configure it to match your mental model.