smtp: throw an exception if the TO is not defined

git-svn-id: https://svn.fournier38.fr/svn/ProgSVN/trunk@3735 bf3deb0d-5f1a-0410-827f-c0cc1f45334c

smtp.php

@@ -173,6 +173,9 @@ class smtp
     $from = $this->cleanMail ($from);
     if (is_string ($to))
       $to = array ($to);
+    if (! is_array ($to) || count ($to) === 0)
+      throw new \Exception ("Can't send mail: no valid recipient provided",
+        500);
     $this->putLine ("MAIL FROM: $from\r\n");
     foreach ($to as $t)
     {