A State Department official provided Fourth of July party invitations, subtle coaching and cheerleading, and inside information about Secretary Hillary Rodham Clinton’s meetings to a Washington lobbyist for a Canadian company seeking permission from the department to build a pipeline that would carry crude from the oil sands of Canada to the Gulf of Mexico.

E-mails released Monday in response to a Freedom of Information Act request filed by the environmental group Friends of the Earth paint a picture of a sometimes warm and collaborative relationship between the lobbyist for the pipeline company, Trans-Canada, and officials in the State Department, the agency responsible for evaluating and approving the billion-dollar project.

The exchanges provide a rare glimpse into how Washington works and the access familiarity can bring. The 200 pages are the second batch of documents and e-mails released so far.

They also offer insight into the company’s strategy, not revealed publicly before. TransCanada lobbyists exchanged e-mails with State Department officials in July about their intention to drop their request to operate the Keystone XL pipeline at higher pressures than normally allowed in the United States to win political support, but then suggested they would reapply for the exception once the project had been cleared.