Virginia governor Mark Warner said, "Half the world's internet traffic passes through Virginia, so it is appropriate that we give our prosecutors tools to go after this costly and annoying crime.
"Before this law, legal action was almost not worth the trouble for prosecutors - which is no message to send to our internet industry in its fight against the spam invasion."
But Stephen Keating, the executive director of The Privacy Foundation, a non-profit advocacy group in Denver, said the new law could present challenges in enforcement in the cases of spammers who are in other states or countries.
"I think they should be applauded for forcing the issue," Keating said. But he predicted that major spam producers would try and draw out any legal action that threatens them.
"It will undoubtedly end up at the Supreme Court. Spammers claim this is a free-speech activity," said Keating.
Other US states have enacted laws making e-mail abuse a civil crime. Similar bills have been considered on the national level during the past few years, but no federal action has yet been taken.
According to Warner, civil penalties have not held back the tide of spam so the tougher approach was needed.
Under the law, senders can be prosecuted if they consciously alter either e-mail header or other routing information and attempt to send either 10,000 messages within a 24-hour period or 100,000 in a 30-day period.
The sender can also be prosecuted if more than $1,000 in revenue is generated from a specific transmission, or $50,000 from total transmissions.
The underlying Virginia statute that the new felony penalties enhance has survived previous constitutional challenges in cases brought by both AOL and Verizon.