For non-urgent communications, use email(ashe@ethz.ch). Most things are non-urgent.
For urgent issues(that can be addressed immediately), use skype(ellliottt). For items that cannot be addressed immediately, use email, as I cannot snooze skype messages and will forget.
I do not have email notifications enabled and do not check emails continuously.
Emails that cannot be addressed immediately(in 30 seconds) will likely be snoozed until another day, perhaps the weekend.
I often send emails outside work hours(at night and at the weekend), and don’t mind receiving emails outside work hours. We agree there is no expectation that the recipient will respond(or even read the message) until the next work day(with the obvious exceptions, such as a joint impending deadline).
Email Norms
Sources