If individuals want to automatically refuse foreign mail or block all mail from a specific sender, they must submit a written request to the USPS to withhold correspondence for up to two years.
1 liter = 33.8140226 US fluid ounces. 1 US fluid ounce = 0.0295735297 liters. Note that this is for fluid ounces, not dry ounces. A fluid ounce is a measure of volume, just like a liter is. A dry ounce is a measure of weight.
Measure it out with a 1 liter bottle and a 1 cup measure. To calculate it 1 fluid oz equals 0.02957 liters, so 8 fluid ounces equals 0.2366 liters. That's about a quarter of a liter...so there are about 4 cups per liter. I'll let you do the calculations for the exact number.