Synchronize Comcast mail contacts

It isn't. In order for that to happen, Comcast would have to offer mail as asn IMAP connection which they do not.

Actually, you can download the Xfinity Connect email app and have access to your Comcast contacts on the iPad. You can even import your iPad contacts to the Comcast Server and then all of your contacts are in one place in the app and on the server.

You can even set up additional folders on the server with Comcast mail and they will sync with the iPad via the app

On your mac you can go to this link: http://customer.comcast.com/help-and-support/internet/sync-contacts-in-xfinity-c onnect/