HTC Desire phone & spam

jackyann

Hello, newbie to the techie forum, hoping for some very specific help.
We (DH & I) got a HTC Desire phone in order to be able to access emails from our phone ( we're about to start a new build - another story!).
We put on 3 addresses: our own private addresses + a joint one that we use for the build.
Both of us shop a lot on-line and attract a huge amount of spam. we normally take no notice as it all goes directly to spam folders. On this phone however, there are no filters, and the enormous download eats into our allotted megabits.
Orange (our provider) referred us to HTC and they say we should organise it through yahoo. The yahoo filters work fine on our accounts when accessed through ordinary computers.
We may have to delete our own accounts and just use the joint one - which has not so far attracted much spam, but as we start to buy stuff through it, it may do so.
Any ideas? Thanks!