add lang key

langs/english.php

@@ -592,4 +592,4 @@ $_LANG['logInToWebmail'] = 'Go To Webmail';
 $_LANG['addonCA']['breadcrumbs']['Zimbra Email'] = '';
 
 // thurdata soap error codes
-$_LANG['account.ACCOUNT_EXISTS'] = 'Email Adresse existiert bereits';
+$_LANG['account.ACCOUNT_EXISTS'] = 'Address already in use';