Cisco Systems' purchase of email security specialist IronPort Systems is another sign that <A HREF="http://news.zdnet.com/2100-1009_22-6147760.html?tag=nl.r23660">big-name vendors are taking over the spam fight,</A> analysts say. Upon completion of the $830 million cash and stock deal, networking giant Cisco will join Symantec and Microsoft as a leader in the email security arena. Those other companies entered the market via acquisitions and product development of their own.