I prefer that efforts focus on preparing the half-map scenarios (Fascist Tide and Day of Infamy), and PBEM playing.
There is no point to developing a 100% pure PBEM mode where every single decision point in the game is handled by email and the MWiF software handles all the resulting email. That will just never happen.
The game is already highly playable via email.
You just have to do a minor amount of the emailing required, on your own. You can even play a game completely by email communication if you find an opponent willing to answer an endless series of emails like this in J/F 1942: "A German ship enters the North Sea. Does the CW intercept?" next "The German ship enters the Faeroes Gap. Does the CW intercept?" next "A German ship enters the North Atlantic. Does the CW intercept?" next "A German ship enters the US East Coast. Do the Allies intercept?" break point here for multi-player as USN and RN each have ships in zone, so each must answer question. The Allies decide to intercept. They succeed. Email to German player: "Does ship stop moving". German player answers no. Interception Combat begins. Next email: "Do Allies wish to add aircraft to sea zone?" and on and on and on. Air Combat would often be even worse.
Those questions do have to be answered - that is part of playing this game - but no one is going to choose to answer them one at a time, email by email by thousands upon thousands of emails like that. And your next tiny decision has to wait for a response email from your opponent.
And despite that, it could still be done via pure email, if 2 opponents agree, but if you aren't doing those question-response emails somewhat live by pre-arrangement, the game will move at probably a Real Time pace - 6 years to play out the war, maybe longer. And if you both agreed to do a naval movement phase at 8pm this evening, email would be by far the slowest possible way to answer those questions, compared to Internet chat, Skype phone call, mobile phone text, screen sharing, your choice.
The opponents must communicate all through each side's "turn". Electronic communication can be used to do that, and is. It is in no way difficult. A pure, one-email-at-a-time approach would be the worst possible way to play this game.