Lotus notes version 8 only supports this functionality.
Lotus notes 6.5, 7, 7.5 are not supporting this functionality.
Lotus 8 version : steps to recall unread sent email.
You simply open the Sent view of your Lotus Notes V8 mail file, highlight the mail you want to recall, and click the Recall Message button in the Action bar.
After you click OK, the recall request is acknowledged with a dialog box. If everything is set up properly, the messages are removed from the recipients’ mail. You receive a report telling you which messages were recalled or not.