Back in 2013, the U.S. Postal Service and Staples had a great shared idea: mini post offices in Staples stores would give customers flexibility and the postal service some extra cash. Problem is, the folks staffing these in-store post offices were Staples employees, which didn’t sit will with the union representing postal workers.

Members of the American Postal Workers Union called for a boycott of Staples, and they also protested and handed out leaflets outside of stores that were part of the pilot. Members of other unions joined in, including the American Federation of Teachers, which passed a resolution that encouraged teachers and families to do their back-to-school shopping elsewhere.

Staples scaled back the plan shortly after that resolution, doing away with the dozens of mini-post offices and instead adding hundreds of stores to the postal service’s Approved Shipper Program. That limited the menu of USPS services available at Staples, but postal workers didn’t want those services available there at all.

“It’s an example of the narrow, near-sighted view winning over the broader, long-term strategy,” former Postmaster General Patrick Donahoe said in a speech as he left office in 2015, warning that not expanding postal services outside of post offices would mean less money for the postal service and less convenience for consumers.

APWU president Mark Dimondstein told Bloomberg that the union took action because it predicted the logical end of the plan: retailer post offices staffed with lower-paid store employees replacing neighborhood post offices staffed with postal workers.

Staples “would have had full-blown post offices, not staffed by postal employees but rather Staples employees, and the Post Office also would have used that model to spread to other major retailers,” Dimondstein explained.

The post office’s outside watchdog, the Office of the Inspector General, observed in a report earlier this year that packages from Approved Shipper Program partners could actually cost the USPS more money by making mistakes, including sending along boxes without enough postage and completing the paperwork for certified mail incorrectly.

In November of 2016, the National Labor Relations Board ruled that the USPS had violated federal labor law in beginning the mini-post office program and in making Staples part of the Approved Shipper Program instead.

It found that the USPS had kept information from the union, including its projection that making postal services available elsewhere would mean fewer post offices and clerks would be needed. NLRB recommended ending the relationship with Staples, and the USPS announced today that it will do so. The chain’s status as a postal partner will end in March.

A Staples spokeswoman confirmed to Bloomberg that the chain would be ending its USPS relationship, but UPS shipping service would still be available in stores for customers in need of shipping services.