rewrite.js

var Address = require('./address').Address;
var rewrite_to = 'steve.freegard@gmail.com';

exports.hook_data = function (next, connection) {
    var txn = connection.transaction;
    // Use outbound...
    connection.relaying = true;
    var addr = new Address(rewrite_to);
    txn.rcpt_to = [ addr ];
    return next();
}