There would definitely be some level of revenue being driven off these. It is an interesting case where apart from the software it didn't cost them anything to

There would definitely be some level of revenue being driven off these. It is an interesting case where apart from the software it didn't cost them anything to get the email address, so getting a higher unsubscribe rate doesn't seem so bad. (As opposed to discounts/ deals/ competitions) you might normally run to get someone onto a mailing list.