Just to let you know, Red Winter works great as PBEM. the attacking player announces his attacking units and any support and hands off to the defender who will then announce his support if any and then will resolve the combat, passing back to the active player to announce the next combat if any.
I've found it even easier if you get used to over lapping logs.
i) attacker announces combat + support
ii) attacker leaves a space in log for defender to declare their support
iii) attacker rolls support
iv) passes log to defender
i) defender declares and rolls their support
ii) defender rolls the final combat and hands back.