When a redirect using the external URL is used, the 302 HTTP status code is used. The new PageTS Config option allows using different codes:
TSFE.jumpURL_HTTPStatusCode = 301
Moved Permanently
TSFE.jumpURL_HTTPStatusCode = 302
Default – moved temporarily/redirect
TSFE.jumpURL_HTTPStatusCode = 303
Other
TSFE.jumpURL_HTTPStatusCode = 307
Temporary redirect
More info:
RFC: Bug #3787: Patch: new option TSFE.jumpURL_HTTPStatusCode = 30x
http://bugs.typo3.org/view.php?id=3787