(UK law here, implementing EC directive)
> a person shall neither transmit, nor instigate the transmission of, unsolicited communications for the purposes of direct marketing by means of electronic mail unless the recipient of the electronic mail has previously notified the sender that he consents for the time being to such communications being sent by, or at the instigation of, the sender.
http://www.legislation.gov.uk/uksi/2003/2426/regulation/22/m...
It's unlikely anyone would bother with someone who sent 600 emails, especially if she agrees not to send any more to an individual that complains to her.
Edit: bprieto's point about individuals vs businesses is very relevant -- the emails were sent to marketing companies, so they aren't spam under this directive.