From: Portaferry, N. Ireland
I've played 3 allied PBEM games up to near the end of 1942 and have held a line at Chittagong, Changsha and Xi'an on the Asian mainland. If my opponents were a bit more aggressive they could certainly have taken New Caledonia and Fiji but haven't yet and probably won't now I have carrier parity.
A crucial aspect of play I've found has been sending all possible production from the UK and a lot, around 40 units from the US to India. With that boost, after you buy out the garrison divisions turn 1 for cheap they get reinforced in a couple of turns and India can soon be buying more divisions or even corps sized units with their massive manpower/logistics. The Indians can set up a first defensive line at Chittagong and fall back to Dacca then Calcutta. Even if Calcutta falls, it's fine as the Indians can be pumping out a division every turn by 1943. Ceylon is 100% lost if the Japanese want to take it though, not worth using carriers to try to defend.
In China, Changsha should fall by the end of '42 given good Axis play but it shouldn't be too hard to hold Chungking/Chengtu due to the horrible supply lines the Japanese have to use to get there. In the north, as long as you move the communist armies south straight away to defend the railroad, Lanzhou shouldn't be a feasible objective for the Japanese.
Australia looks nasty until you realise that there really isn't anything worth defending other than the Melbourne, Sydney, Canberra area and if the Japanese want to challenge you for that, it should present a chance for a favourable carrier battle under your land based air. Places like Cairns, Darwin, Rockhampton are fine to give up.
The only things you can't afford to lose are Delhi, Lanzhou (the ComChi's surrender), Sydney (for the level 5+ port in the South Pacific) or more than one carrier. Until you outnumber the Japanese carriers the allied CV fleet should be sitting in Sydney as it's the most vunerable key spot and it never moves anywhere dangerous unless covered by at least two land based naval bomber units. In a 4v6 fight the Japanese usually win 3-1 in carriers sunk.
Picture of how my Burma lines 1-2 are usually set up from a new PBEM game. You can see India at nearly 70 production already with more to come soon and almost all divisions non-garrison and high strength. One garrison left at Madras.
Is it possible to defend India from both a land attack through Burma and a naval invasion, as I said this is my first game but it doesn't look possible to me if Japan attacks before India can get anything built or the UK can transport across some units ?
I don't follow why Japan would need to expose their carriers to take out Australia. They invade the North East early and then just work down the coast by land using the rail line to support a strong force of infantry with some air units.
China I don't know, will see how our two games pan out during the summer but it looks like it will be difficult for China if India has fallen.