It is important to note that any "previewmp3" circulating that is not from official DSPs (Spotify, Apple Music) or Pitbull’s official YouTube channel is likely an unauthorized leak. The official track was released on Mr.305/Polo Grounds and RCA Records on April 16, 2013, as part of Pitbull’s album Global Warming: Meltdown .
Regarding the specific file title you provided ("previewmp3"): These files were often circulated on blogs before the official iTunes release. pitbull feel this moment feat christina aguilera previewmp3