Aviran reports, by way of Ynet (and let me just preference this with one big sic),

The Israeli National Institute of Standards have being practicing in a controversial activity. In the name of “helping to inform the public” the National Institute of Standards hired a company to send email messages thru the company’s distribution list (in other words spam list).
An Israeli hacker tired of getting these spam messages have taken an action and hacked to the server where the email database is stored. After he got access to the database he deleted all the data from the spammer’s database, deleted all user names and passwords to the database and changed the database’s admin password.
“After the third time I got these spam messages I managed to hack into their management system and deleted their entire database,” said the hacker, identified himself as Anti-Spammer.

Source.