The short answer is most likely not. Technically an email can be recalled only on an Exchange server, when both, sender and recipient use the same server, and the recipient hasn't opened the message from the server yet. MS Exchange is typically used in a corporate environment in connection with Outlook. Email providers normally don't use Exchange as email server, and their server software most likely doesn't support 'recalling' a message. You're out of luck if sender and recipient use different email providers. Also see http://kb.mozillazine.org/Recall_a_message

Thanks for your help.