Technical :
Use GMX through a proxy, or better, setup your own SMTP server and spoof your IP and MAC address.
Social :
The best trick is to send a stranger the original message from a hotmail account through proxy (with HTTPS), and use the end-recipient (your victim) in the from-address.
That way a stranger (or a few strangers) will respond to your message but send it to your victim.
Works great !
