You haven't posted enough information to be sure, but the message is probably a phishing email, a scammer attempt to steal login and account information. If you check your email with Comcast's Xfinity Connect webmail, look for the XFINITY Verified Email logo next to any message that claims to be from Comcast/Xfinity (see https://www.xfinity.com/support/articles/comcast-verified-email).
Please see Comcast Email Phish or Legit? How to Tell (and rules for posting) for more information about identifying phishing emails. The article is somewhat out of date, but still useful.
Samples of recent phishing messages can be found at http://constantguard.comcast.net/help/alerts under "Top Phishing Scams".
@nollkc wrote: I'm confused, is there something I'm supposed to do to keep my account active? I've never heard of such a thing.
If you got a notice about Comcast's new Email Activity Policy, see https://www.xfinity.com/support/articles/email-activity.