A significant rise in the global volume of spam in the past two months has security analysts worried that bot nets are increasingly being used by spammers to stymie network defenses erected to curtail bulk e-mail.

Estimates of the magnitude of the increase in junk e-mail vary, but experts agree that an uncommon surge in spam is occurring. On the low side, Symantec, the owner of SecurityFocus, has found that average spam volume has increased almost 30 percent for its 35,000 clients in the last two months.

Story continues at securityfocus.com