A new study from Arial Software, which makes email-marketing software, found 67% of businesses sending promotional newsletters didn't comply with CAN-SPAM rules, but that didn't automatically mean they were spamming their recipients.

The company spent six months subscribing to and analyzing the performance of email newsletters sent by companies of all sizes -- including brand-name, Fortune 500 companies -- and found that only 3 of the 1,057 it subscribed to engaged in what the survey takers considered spamming: sending high-volume commercial email or emails with unsubscribe links that didn't work.

Although the survey didn't name the three apparent spammers, it did bust 12 that apparently ignored unsubscribe requests, including About.com, Backcountrystore.com, Knight-Ridder, Kraft Foods, Omaha Steaks and Camping World.

Some other findings:

-- 51% didn't offer an unsubscribe link

-- 93% didn't confirm new addresses. That doesn't break the law, but it does make an emailer more vulnerable to spamming claims by people who say their addresses were added without their permission. In addition, 72% of companies didn't send follow-up emails to confirm opt-ins.

-- 45% didn't identify themselves clearly in their email messages.

-- 36% sent no emails in the six months since Arial workers opted in to their programs.

The survey has lots more statistics and suggestions for why companies aren't meeting the law or following email best practices. Download the survey here.