An 18-year-old in the US has become the first person to be charged for sending out unsolicited instant messages, otherwise known as "spim".
The New York man is accused of sending out an estimated 1.5 million instant messages advertising porn and mortgage deals to users of US networking site MySpace.com.
He is alleged to have threatened the site by promising to reveal the way he mounted the attack to others if the site did not officially endorse his instant messages.
He was arrested at Los Angeles airport after flying in to what he thought would be a business meeting with the owner of the site, court papers say.
Instead, he was arrested by federal agents and charged with violating federal anti-spam laws, abusing MySpace.com computers and attempting extortion.
It is believed the man created thousands of MySpace.com accounts and then sent through the unsolicited instant messages automatically.
Instant messaging is increasingly used in businesses and homes. Just like e-mail, it can be targeted by spammers and hackers. Microsoft recently issued a patch against security openings in its MSN Messenger service.