[mindfrost82]

I'm closing my thread now, but I'll post the solution in case someone needs it in the future. I found it in a post over at XDA:

If you tap and hold on each folder you can then select 'folder options'
then in the drop down box you can select 'get full copy of message' and also 'only display messages from the last X days'
Do this for any folder you want to synchronise and you're good to go
When you go back to these options at a later time it would appear that the settings you chose arent sticking, this is infact misleading as all it is doing is putting the options back to default by appearance, but clicking 'ok' after setting each folder does infact stick the setting.