Especially when the team members are operating in multiple time zones, it can be difficult to recall what time it is in which zone. Everyone needs to know what other members are doing when you need them. It is very unpleasant to be called when you are sleeping after a difficult day.
Set basic guidelines
How much time should it take to reply to an email? Should everyone in the team send an acknowledgment when he or she has read a message? Under what circumstances does the boss or specific teammates have to be carbon-copied? These rules may appear to be trivial, but they can greatly affect the morale and trust of whole team.
Don’t impose the rules from the top…
… because everyone may get the feeling that the rules are too strict and excessively pedantic. However, since you need these rules, you have to find a way that will not cause resistance. Let the team develop these rules during a group discussion. Everyone is much more likely to stick to the rules he helped to design. The exact same guidelines that would otherwise be rejected and frowned upon will be perceived as reasonable and beneficial.