I'm not sure there's a way to get it to send you the dollar amount in the e-mail. You can set it up to e-mail you when the statement is ready (paperless statements) and you can set it up to e-mail you any number of days in advance (default is 10, but you can change it) as a reminder. But either way you need to log in to see the amount.
I really hate that Mint changed their billing, it's totally useless to me now. I always had it set up to remind me to pay my rent the day before it was due (I try to always pay 1 day early, so if I forget to drop it off that day, it's not actually late). Now it comes a week in advance and I've forgotten all about the reminder by the time I actually have to drop it off.