where parameter "link" is the base64_encoded string:
http://localhost/j/index.php?x=y Hai I am a spam message! Would you like
to buy all sorts of fake stuff? SPAM SPAM SPAM
This is important as the domain at the beginning must match the domain
being relayed against.
Now, fill out the form with victim email as "Email To" parameter & send.
These issues have been reported on each version's respective bug tracker:
Joomla! 1.6.0:
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=24288
Joomla! 1.5.22:
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=24289