All you need to do is make sure the account is configured on the phone using the IMAP protocol. It should have auto-configured it that way for you when you enabled the account on it since Comcast accounts are IMAP compliant by default. The only way to worry about it on the pc is if you are using a desktop client like Outlook or Thunderbird. If you are not using a client there is nothing else for you to configure. So if the phone is not using IMAP, delete the account and re-create it from scratch, and let it configure it for you after you put in your user ID and password.