Storing Unopened Mozzarella
My best advice would be to adhere to the manufacturer's guidelines, and push them at your own risk. Cheese doesn't usually go bad "all at once" but you can definitely get sick from eating spoiled or moldy cheeses.

The most common notice I have been able to find for various brands available for ordering online reads something like this:


  Freshness is assured in unopened package until the date stamped on the front of the package.  Use within 3-5 days after opening or freeze up to 2 months.


Though, I have a bag of mozzarella in my freezer right now, which I purchased at the local supermarket, for which the manufacturer's note states it can be frozen up to 6 months.

Generally, the expected shelf-life of Mozzarella cheese depends on many factors, including:


How the cheese was produced. Some methods spoil faster than others. Typically low-mosture cheeses last much longer (some claiming 6 months or more).
The packaging. Some mozzarella (like other cheeses) comes in specially designed packaging that claims to prolong the life of the cheese.
The temperature of storage. Frozen cheese lasts significantly longer, around 6 times as long.