A City Carrier Assistant to the United States Postal Service, unloads her mail truck after collecting mail on the busiest mailing day of the year for the U.S. Postal Service in Miami, Florida.

The Universal Postal Union agreed to a compromise Wednesday that would allow the United States to set its own inbound postage rates and remain within the organization the Trump administration had previously threatened to leave.

After rejecting a handful of earlier options, more than half the 192-country body voted in favor of "option V," which will allow the US to raise prices for packages arriving from other countries, in exchange for a contribution into the Union's "voluntary fund," which covers security and pensions. Other countries can also adjust prices on US inbound packages next July and on packages from elsewhere by set amounts each year.

"By remaining in the UPU, the United States retains its important leadership role in the global postal system," says Kate Muth, executive director of International Mailers Advisory Group, which includes Amazon and eBay. "Mailers and shippers will see no interruption in service through the critical holiday season and beyond.

Jean-Paul Forceville, the chief negotiator for France's La Poste, told CNBC earlier that the probability was "pretty high" that a compromise would be reached this week to reform the 144 year-old organization along some of the lines the United States has proposed.

The White House has been pushing to raise—or, in postal jargon, "self-declare"—the rate it charges other countries to deliver their packages. Peter Navarro, leading the White House delegation in Geneva, says that a higher barrier to entry would shift demand from cheap goods produced in and subsidized by China to higher-quality goods produced in the US.

"Donald Trump is taking action to address this disparity, which costs the USPS and American consumers millions of dollars each year," Navarro wrote in the Financial Times this month.

To effect the changes as soon as possible, the White House triggered a one-year withdrawal process in late 2018. The UPU convened an "extraordinary Congress" this week to address the US's proposals or risk its withdrawal—and a full-scale disruption of the global mail system.

"I think we know why we are here," said the Kenyan delegate from Posta Kenya, without referencing the United States.

The Trump administration's grievances center on one portion of the mail calculus called terminal dues - the negotiated rate a member government can charge another country when packages under 4.4 lbs arrive on its shores. On Tuesday, the UPU rejected the White House's preferred approach: Allowing all countries to set their own rates immediately.

But the US—along with France, Canada, Japan and others—are now working on a "multi-speed" compromise that would allow these rates to fluctuate on a set schedule.