So on your iOS device, open your Settings app and click on Mail, Contacts, Calendars. Scroll down through that list, and you’ll first see all of the accounts you’ve added there. (I just realized that I have 11. Send help.)
Underneath your accounts, you’ll find the preferences for e-mail. There are all sorts of goodies you can check out in that section, like changing the font size, organizing messages by thread, and configuring how many recent messages will be shown in a mailbox. My favorite change to make there is labeled Preview.
This preference toggles how much of a message’s body is shown in your list of e-mails, so depending on how you configure things, your mailboxes can look like this (with Preview set to “None”):
Or they can look like this (with Preview set to “5 Lines”):
Since I get a metric ton of e-mail every day, I much prefer the “None” option here; that way, I can gobble up more information quickly and decide if there’s anything in the list that I need to deal with immediately. (Heck, just being able to see the sender’s name would usually tell me how soon I need to reply.) If you’re a different type of person and like to have more of a preview of a message before you open it, feel free to set that any way you’d like. Weirdo.