Tesla still refuses to sign a collective agreement with mechanics at its Swedish repair centers. As a result, the Service and Communications Employees’ Union (Seko) said Monday that it will be the latest to join a growing strike and, in solidarity, will no longer handle the automaker’s mail.

This expansive strike began in late October when, after years of failing to get Tesla to sign a collective agreement, IF Metall called on the mechanics it represents to walk off the job at the automaker’s Swedish service centers.

So far, so normal, but Swedish unions aren’t like others. Although the country has no federal minimum wage, the vast majority of workers are protected by collective agreements. That means that even relatively small groups of people, like the 130 or so Tesla mechanics started this strike, can count on the support of members from other unions.

Shortly after the strike first started, Swedish dockworkers announced that they would not unload Tesla vehicles at a handful of the country’s ports. After that didn’t work, they blockaded all of the nation’s ports, and the country’s maintenance workers said they would refuse to clean Tesla facilities.

More: Swedish Tesla Showrooms Might Get Gross, As Cleaners Join The Escalating Strike Against It

 Everyone Seems To Be Striking Against Tesla In Sweden As Postal Workers Join In Too

It’s more serious than it sounds

Now, mail carriers will halt the delivery and collection of mail to Tesla, Euronews reports. That may sound a bit old-fashioned, but it means that the automaker will no longer receive crucial parts required for repairs and services.

Seko’s president, Gabriella Lavecchia, said that Tesla’s refusal to sign a collective agreement with its mechanics is an attempt to gain a competitive advantage by offering its workers substandard wages and conditions. Although Tesla has maintained that it offers competitive wages, what started as a minor conflict with a small number of Swedish mechanics is growing into a bit of a David and Goliath story.

Tesla has been staunchly opposed to unionization efforts, and has been found guilty of illegally retaliating against employees who tried to organize. That means that these Swedish mechanics are the first on earth to strike against the young company. And IF Metall is aware of how monumental its strike could become.

“This conflict is about wages, pensions and insurance for our members who work at Tesla,” said Marie Nilsson, the union’s president, in a press release. “But fundamentally, it is also about standing up for the entire Swedish labor market model.”

It’s not just about Sweden, though. Unions around the world are looking on to see how IF Metall gets on. That includes IG Metall, the related organization that represents German autoworkers, and which has been trying to gain a foothold at Tesla’s Berlin plant. Representatives told Vice that they are following the events in Sweden “very closely and with solidarity for our colleagues.”

Read: UAW Ready To Take On Tesla, Honda, And Toyota In Next Batch Of Talks In 2028

 Everyone Seems To Be Striking Against Tesla In Sweden As Postal Workers Join In Too

Workers in the U.S. may also be watching on with interest. Tesla American employees frequently complain about conditions, from having to deal with bed bugs, to having to suffer racist abuse from their colleagues, and receiving no support from management when they try to speak up. Indeed, the United Autoworkers union (UAW) has suggested that it is interested in helping the automaker’s emplyees organize.

Indeed, Branislav Rugani, the international confederal secretary of Force Ouviere, a French trade union, said that what is happening in Sweden will influence what happens around the world.

“Unions are organized on an international level,” Rugani said. “They talk amongst themselves. When they return to their respective countries, they organize on a local level.”

Victory isn’t guaranteed for Swedish workers yet, though. Reports suggest that Tesla has been working to deliver vehicles to the country over land, and that the impact of the strikes so far has been limited. That leaves question marks about what it will take to make the automaker cave to the pressure, and whether or not it ever will.

 Everyone Seems To Be Striking Against Tesla In Sweden As Postal Workers Join In Too