It is the equivalent of a letter box in the postal system.
"We want them to know the whole postal system is not lousy."
The postal system played a crucial role in national expansion.
Not everyone has a home computer, and most people who do still use the postal system to pay bills.
The postal system was important in the development of modern transportation.
It wouldn't be so bad running the world's largest military postal system except that the troops don't stay put.
Anything sent through the postal system is called mail or post.
She called the Vatican's service "probably one of the best postal systems in the world."
The postal system, they now knew, had been used as an instrument of attack, an important finding.
The postal system however continued to be a public company.