Under the change, UPS Sure Post packages are now only being delivered by UPS drivers, a spokesperson for the International Brotherhood of Teamsters spokesperson told Supply Chain Dive. In the past, the final leg of these deliveries was made by the U.S. Postal Service; now, they will be handled by UPS after the Jan. 1 contract expiration.

A few delivery services might be the blame. According to a report, an expire contract agreement between UPS and the US Postal Service has delayed millions of packages across the country.