In general, freshly boiled water is appropriate for black and herbal teas, but steaming (sub-boiling) is best for green, oolong, and white teas.   A lot of people use boiling water all the time and report their tea tastes fine.  Ultimately, your taste preferences are all that matter, so feel free to experiment a bit with different brewing temperatures.   We always put our suggested brewing instructions on our packaging for each tea, so use that as a place to start.  If you ever find that green, oolong, or white teas are tasting bitter, be sure to try brewing them at a lower temperature first.