This is because boiling honey will drive off some of the delicate flavors. If scum rises while heating or boiling the must, skim it off. It consists of wax, bee parts, pollen, etc., which don't help the flavor of the mead. If you're a winemaker, you'll recognize this method. If you use Campden tablets, follow a recipe or instructions for quantity, preparation, delay times before adding yeast, etc.
Heating is probably easier than sulfiting for the beginning mead-maker.
Yeasts Mead is more a wine than beer, with a final alcohol level anywhere between 10 and 18 percent. Each yeast will impart its own unique characteristic to the mead. Champagne ferments out very dry and has a high alcohol tolerance. Epernay has a fruity bouquet. Flor Sherry has a high alcohol tolerance and contributes a flavor that goes better with sack meads.