diff --git a/phpBB/includes/acp/acp_board.php b/phpBB/includes/acp/acp_board.php
index dd6c731abb..63e2647f02 100644
--- a/phpBB/includes/acp/acp_board.php
+++ b/phpBB/includes/acp/acp_board.php
@@ -615,7 +615,15 @@ class acp_board
 		{
 			add_log('admin', 'LOG_CONFIG_' . strtoupper($mode));
 
-			trigger_error($user->lang['CONFIG_UPDATED'] . adm_back_link($this->u_action));
+			$message = $user->lang('CONFIG_UPDATED');
+			$message_type = E_USER_NOTICE;
+			if (!$config['email_enable'] && in_array($mode, array('email', 'registration')) &&
+				in_array($config['require_activation'], array(USER_ACTIVATION_SELF, USER_ACTIVATION_ADMIN)))
+			{
+				$message .= '<br /><br />' . $user->lang('ACC_ACTIVATION_WARNING');
+				$message_type = E_USER_WARNING;
+			}
+			trigger_error($message . adm_back_link($this->u_action), $message_type);
 		}
 
 		$this->tpl_name = 'acp_board';
diff --git a/phpBB/language/en/acp/board.php b/phpBB/language/en/acp/board.php
index a2bfb43be7..8d6c1c141d 100644
--- a/phpBB/language/en/acp/board.php
+++ b/phpBB/language/en/acp/board.php
@@ -222,6 +222,7 @@ $lang = array_merge($lang, array(
 
 	'ACC_ACTIVATION'				=> 'Account activation',
 	'ACC_ACTIVATION_EXPLAIN'		=> 'This determines whether users have immediate access to the board or if confirmation is required. You can also completely disable new registrations. <em>“Board-wide email” must be enabled in order to use user or admin activation.</em>',
+	'ACC_ACTIVATION_WARNING'		=> 'Please note that the currently selected activation method requires emails to be enabled, otherwise registration will be disabled. We recommend to either select a different activation method or reenable emails.',
 	'NEW_MEMBER_POST_LIMIT'			=> 'New member post limit',
 	'NEW_MEMBER_POST_LIMIT_EXPLAIN'	=> 'New members are within the <em>Newly Registered Users</em> group until they reach this number of posts. You can use this group to keep them from using the PM system or to review their posts. <strong>A value of 0 disables this feature.</strong>',
 	'NEW_MEMBER_GROUP_DEFAULT'		=> 'Set Newly Registered Users group to default',