Under the deal, which will end at 3 p.m. MDT Friday and is available to people travelling between Thursday and March 29, flyers can pay $25 per bag for up to nine bags to ship them door-to-door through FedEx within the continental U.S. Pickup and delivery aren't available Sundays or holidays.

United, which charges customers $25 for their first checked bag and $35 for their second, is hoping to capitalize on convenience sought by the Spring Break crowd, said Jeff Foland, senior vice president of worldwide sales and marketing, in a news release.

Almost every airline has instituted or increased baggage fees in the past year as a way to offset revenue lost by the decreasing amount of travelers during the economic downturn.

Meanwhile, Southwest Airlines, the No. 3 carrier at DIA, is emphasizing in a new series of commercials that it is the only major carrier that does not charge luggage fees.