SMTP to Jabber Gateway

I am looking for a SMTP to Jabber gateway. Here is the idea. You assign an email address to a jabber user. When the user isn’t logged in via a XMPP client, messages are sent to that email address. (or SMS email address). When the user replies the message is delivered to back to the XMPP server (via SMTP or picked up via IMAP/POP3_ for delivery to the original sender.

Anyone know of anything that does this?