You you can. I do now although I barely use my Comcast email anymore (I much prefer Gmail). It will not be push however, you will have to decide how often you want to check your Comcast.net email. Obviously the more often you choose the more battery drain.
Comcast (Xfinity) has an iPhone app that allows you to check your email and listen to your home Voicemail if you have Comcast phone service. I believe you can set that up with push notification.