When my T has been away on holiday in the past, we planned a certain day and wrote it in the diary, when I would email him to tell him how I was doing, and he would reply. That helped me a lot because I could have some contact with T, and I knew when it would be, instead of emailing randomly and then waiting and waiting for him to reply and thinking that something could have happened.
Nowadays we don't need that plan any more really, but the last time T was away I checked if I could contact him "just in case" and he told me when he would look at his email for a just-in-case scenario. And in the end I did contact him! And that was fine.