Quote some text when you reply. Tap the insertion point, then select the text you want to include. Tap , then tap Reply. You can turn off the indentation of the quoted text in Settings > Mail, Contacts, Calendars > Increase Quote Level.

Send a message from a different account. Tap the From field to choose an account.

Change a recipient from Cc to Bcc. After you enter recipients, you can drag them from one field to another or change their order.