You could 'hack' any spying tendency though, just set up a system to send emails early morning, late at night, at weekends.

Then come annual review time, your boss can be impressed by your dedication.

This is off the top of my head, and does have the obvious flaws of being obviously automated from the sending machined perspective, and emails might not be a sign of work in your particular job. It probably has unobvious flaws as well, so isn't career advice.