Older emails not showing on iphone/iPad but do show if using windows outlook

Hi, something driving me nuts, icloud email account on iphone and ipad and icloud via a browser wont show any sent items over around 6 months old but when using icloud for windows via outlook all the sent mail is there going back years , if you put in a outlook account for instance in the iphone it gives you the option to sync days /weeks /months / or everything but there is no option for that with the default icloud account - so basically to see older sent items i have to use outlook on a windows computer which kind of defeats the purpose - any suggestions ?