United Parcel Service says its worldwide holiday season package volume is expected to be up about six percent over last year, and the company expects a record number of parcels to be processed at the UPS Worldport sorting hub in Louisville.UPS relies on an army of part-time workers to handle the holiday rush. The massive Worldport facility was braced to sort some three million pieces on Thursday.Package handler Kayn Genesis has been with the company for 18 years."It’s tedious, but you know it’s coming. You’re prepared for it," he said.UPS Spokesman Mike Mangeot says the uptick in the shipping business coincides with recent growth in e-commerce."We do business with 24 of the top 25 online retailers. Everybody from Amazon to Zappos to you name it. Customers absolutely embrace that and we’re happy to be the fulfillment arm of their shopping," Mangeot said.Mangeot says UPS will deliver packages through Christmas Eve.