Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.468
diff -u -r1.468 system.module
--- modules/system/system.module	17 Apr 2007 07:19:39 -0000	1.468
+++ modules/system/system.module	23 Apr 2007 06:59:24 -0000
@@ -574,7 +574,8 @@
     '#type' => 'textfield',
     '#title' => t('E-mail address'),
     '#default_value' => variable_get('site_mail', ini_get('sendmail_from')),
-    '#description' => t('A valid e-mail address for this website, used by the auto-mailer during registration, new password requests, notifications, etc.')
+    '#description' => t('A valid e-mail address for this website, used by the auto-mailer during registration, new password requests, notifications, etc.'),
+    '#required' => TRUE
   );
   $form['site_slogan'] = array(
     '#type' => 'textfield',