Help Mail settings on HTC Sense On Desire 2.2

[Steve1976]

I have a Vodafone branded HTC Desire, with the Froyo 2.2 update, software number 2.10.161.2. Before I did the over the air update to 2.2, my email would come through when i refreshed the mail (set it like this to conserve battery power), and the mail from the last, I'd say, 3 days, stayed on the phone which I found very useful. Now, without changing any settings, everytime I refresh the mail and get the new mail into my phone from the server, all existing downloaded mail disappears which is annoying! Does anyone know the settings I need to stop this happening and retain the old mail for a few days at least as before?

Thanks for looking