There are different theories on how to properly brew tea.
I drink a lot of black tea, such as Earl Grey & English Breakfast and I think it is best to have the water as hot as possible when pouring it onto black tea. However for green tea , I find it better to have non-boiling water. If the water is very hot green tea can turn bitter during the brewing process.
Here are two links that lead you to posts about tea preparation that I found informative:
lancaster.unl.edu/food/ciqtips-jan04-tea.htmimperialteagarden.com/brewtea.html