I got this email from Comcast.  Anyone know if it is valid.  I have a Macbook Pro.  Not sure if I should ignore it or what.  When I go to the site to do what they say, it says I have to download Norton, and it is free for comcast customers.  I don't use an antivirus as its a Mac.  Any help is appreciated;  This is the email I got.


Constant Guard from XFINITY identified that one or more of your computers may be 
infected with a bot. A bot is a malicious form of software that is used to send 
spam, host a phishing site, or steal your identity by monitoring your keystrokes 
without your knowledge. It may be possible you are unaware that your computer is 
infected with a bot.  
We strongly recommend you visit XFINITY.com/BotAssistance (http://www.xfinity.com/botassistance/?CMP=EMC-Email1&utm_source=Notification&utm_medium=Email&utm_campaign=Email1) 
for important information on how to remove malicious software from your 
computer(s).