McAfee on Thursday announced plans to acquire managed email and web security vendor MX Logic for at least $140 million. McAfee said the acquisition would bolster its cloud-based security portfolio. The deal is expected to close during the third quarter of 2009.  If the deal goes through, MX Logic staff will be integrated into McAfee's software-as-a-service business unit. McAfee stands to gain MX Logic's 40,000 customers, representing four million end users. — AM