Agree with the others - emailing T can be done at any time. They choose when to check it. If your T is one that has email sent to their phone...well, they can set the alerts to not notify them during certain hours.

The only time I consider what time I'm sending an email is if I know I'll be anxiously waiting a response. My T tends to check emails first thing in the morning and again at the end of the work day. So, the closer I send to those times, the more quickly I'll get a response. I also know that my T does not have her email pushed to her phone (I asked), so I don't worry about that.