They have a mail facility. People who receive mail and parcel it out or send it out as the case may be. I do not think there is a public post office in the White House.
White House Office was created in 1857.
White House Shipping is a U.S. - based international shipping company known among others for shipping rates below those of the U.S. Post Office.
the president's office is located on the third floor of the white house
White House Military Office was created in 1957.
Mule
The White House Office
In the White House
The president's cabinet is a group of people that run the various federal departments. All of the have offices in Washington, DC. They rarely meet as a group nowadays, but if the president calls a meeting, it will probably be held in the White House.
White House Office of Urban Affairs was created in 2009.
White House office
The Office of Management and Budget, (OMB), along with the President controls the White House budget. OMB is the largest office in the White House.
The Oval Office.