You could maybe increase the daily email to a paragraph or two and require him to tell you about his day, every day, like a journal entry. And I don't think you should let days missed slide, unless you approved ahead of time (or if you want to give a pre-approved list of "permitted reasons emails can be missed", or something like that).

The first step towards control is just plain learning about the person. The greater the detail, the greater the control. You can increase the necessary detail as you go. For example, you can start with "I ate lunch at one o'clock" as being acceptable, then after a few of those require what was eaten for lunch, then why that meal was chosen, then after doing that for awhile you'll get to know his routine so you can alter it.

That's just one example. Food is an easy thing because you know a person has to do it every day. Same with sleeping, peeing, getting dressed, etc.