So essentially you're saying is that the subscription *is* an email subscription, but I cannot edit delivery settings.
That's right. Currently, you can't edit delivery settings for Jetpack sites like you can for WordPress.com sites.
If updates follow my default delivery settings, then I won't receive updates by email since my default Reader setting is "no email delivery".
I've confirmed that there isn't a way to override default "no email delivery" settings to receive emails from Jetpack sites. I will bring this to our developers' attention.
One workaround could be to subscribe for email updates on Jetpack sites using a different email address. Some email services such as Gmail allow you to create forwarders "on the fly" by adding a dot or plus sign after the first part of your address, which will deliver mail to you normally but be treated as a unique email in our database.
So for example, if your email were [email redacted] - you could enter [email redacted] or [email redacted] in the subscriptions box and you should then receive updates by email. I realize this is an extra step and apologize for the inconvenience.