Columbia Mail

Columbia Mail is the primary communication service run in Columbia in BioShock Infinite. It was founded in 1894 and functioned out of Columbia Post Office. The Vox Populi believe it to aid in spreading lies of The Founders, and as such, they vandalize their property with specific detail.

E3 2011 Gameplay Trailer
During the E3 2011 Gameplay Trailer, Booker DeWitt must head here on his way to Comstock's house. He witnesses a postman being executed by the Vox here, and it later thrown inside one of their buildings by The Songbird.