Staging and development sites typically have real outbound email turned off, and for good reason (see https://wiki.civicrm.org/confluence/display/CRMDOC/Moving+CiviCRM+instance+from+production+to+staging, for example).
CiviCRM-specific ways to do this include the "Redirect to Database" setting (at /admin/setting/smtp?reset=1), and setting
define('CIVICRM_MAIL_LOG', ...) in civicrm.settings.php
Unfortunately, it's rather tedious to examine outbound email when testing things like tokens, templates, etc. As a developer I can see them in the log file or database, but that's not much good for user acceptance testing.
Is there an easy way for users to read the outbound CiviCRM email that's been sent to a log file or to the database?