Spam fell to less than 50 percent of all email in June, the lowest in a decade, Symantec says. The levels of spam have been slowly falling since 2010. Network providers are more tuned into the problem and take action faster when there are issues on their services. Law enforcement, companies including Microsoft have aggressively gone after some of the largest botnets over the last few years. The cost of entry into the spam business is rising as the likelihood of a return falls, so it’s less of an incentive to spam.”]