To Mauld,
Due to the fact that your are flying at out of Newark I assume you are flying United or JetBlue. So what they do is give you two different kinds of barcodes for your boarding paes. One is for if you want to print your boarding pass out and another is for if you want to use your mobile boarding pass. Meaning you can't print out the barcode that is used for your mobile device. And you can't use the printed barcode on your device. The email you received was about the copy of the printed boarding pass barcode with can't be used on your mobile device. If none of this made sense yes it's fine to use the mobile boarding pass.