Don't email users who are sandboxed

If sandboxed or silenced, don't email the user any notifications.

classes/User.php

@@ -658,6 +658,21 @@ class User extends Managed_DataObject
         return $this->getProfile()->isSilenced();
     }
 
+    function receivesEmailNotifications()
+    {
+        // We could do this in one large if statement, but that's not as easy to read
+        // Don't send notifications if we don't know the user's email address or it is
+        // explicitly undesired by the user's own settings.
+        if (empty($this->email) || !$this->emailnotifyattn) {
+            return false;
+        }
+        // Don't send notifications to a user who is sandboxed or silenced
+        if ($this->isSandboxed() || $this->isSilenced()) {
+            return false;
+        }
+        return true;
+    }
+
     function repeatedByMe($offset=0, $limit=20, $since_id=null, $max_id=null)
     {
         $stream = new RepeatedByMeNoticeStream($this);

lib/mail.php

@@ -737,7 +737,7 @@ function mail_notify_fave(User $rcpt, Profile $sender, Notice $notice)
  */
 function mail_notify_attn($user, $notice)
 {
-    if (!$user->email || !$user->emailnotifyattn) {
+    if (!$user->receivesEmailNotifications()) {
         return;
     }
 
@@ -747,12 +747,13 @@ function mail_notify_attn($user, $notice)
         return;
     }
 
+    // See if the notice's author who mentions this user is sandboxed
     if (!$sender->hasRight(Right::EMAILONREPLY)) {
         return;
     }
 
+    // If the author has blocked the author, don't spam them with a notification.
     if ($user->hasBlocked($sender)) {
-        // If the author has blocked us, don't spam them with a notification.
         return;
     }