Changes to the delivery standards of the United States Postal Service are expected to cause delays in mail delivery for many Americans as early as this weekend, adding to the concerns many postal workers have about the future of the post office, and raising more questions about the motives of embattled Postmaster General Louis DeJoy.

The planned slowdown is part of DeJoy’s 10-year plan for the post office that he unveiled earlier this year.

Under the guidelines of the plan, the USPS will implement new standards for its first-class mail, lengthening delivery time for about 30 percent of its volume. That means letters, packages and magazines traveling longer distances could take up to five days to get to their intended destinations, instead of two or three.

“These new service standards will increase delivery reliability, consistency, and efficiency for our customers and across our network,” said Kim Frum, USPS spokesperson, in a written statement to NBC News, noting one-third of first class mail and seven percent of periodicals will be affected by the changes.

“Standards for single-piece First-Class Mail traveling within a local area will continue to be two days. The Postal Service will increase time‐in‐transit standards by 1 or 2 days for certain mail that are traveling longer distances.”

Expected to be especially hard-hit by the recent changes: residents of rural communities.