diff --git a/interface/web/mail/form/mail_user.tform.php b/interface/web/mail/form/mail_user.tform.php
index 2cab87dc4cc50038a13f64ff42d9ee321cf2b2a8..1f2e99203915d52e77401227573bf18ac31f6c95 100644
--- a/interface/web/mail/form/mail_user.tform.php
+++ b/interface/web/mail/form/mail_user.tform.php
@@ -86,7 +86,7 @@ $form["tabs"]['mailuser'] = array (
                     0 => array (  'type'  => 'UNIQUE',
                             'errmsg'=> 'login_error_unique'),
                     1 => array (  'type'  => 'REGEX',
-                            'regex' => '/^[a-z][\w\.\-_\+@]{1,63}$/',
+                            'regex' => '/^[a-z0-9][\w\.\-_\+@]{1,63}$/',
                             'errmsg'=> 'login_error_regex'),
                   ),
       'default' => '',