By ByteBot
German state Schleswig-Holstein hit a major milestone in October 2025, completing the migration of over 40,000 government email accounts and 100 million emails from Microsoft Exchange to open source alternatives. Moreover, the €15 million annual cost savings from ditching the Microsoft stack across 60,000 civil servants makes this one of Europe’s largest government open source deployments—and a critical test of whether digital sovereignty can work at enterprise scale.
What They’re Actually Replacing
This isn’t a small pilot project. Schleswig-Holstein is replacing Microsoft’s entire productivity stack across 60,000 government workstations. Exchange Server becomes Open-Xchange, Outlook becomes Thunderbird, Office becomes LibreOffice, SharePoint becomes Nextcloud, and Teams becomes Jitsi. Furthermore, even Windows is on the chopping block, with a gradual Linux rollout already in testing.
The October 2025 email migration milestone moved 40,000 accounts and over 100 million emails and calendar entries in six months. Additionally, LibreOffice is now deployed to 80% of workplaces outside tax administration, affecting 30,000+ employees across the State Chancellery, ministries, judiciary, and state police. However, here’s the reality check: 20% of workplaces still require Microsoft programs due to specialized applications that lack open source alternatives. Consequently, this 80/20 hybrid model is probably what most large organizations will end up with.
The Business Case: Less Than One Year Payback
The financial argument is hard to ignore. Schleswig-Holstein will save over €15 million annually in Microsoft license costs. Despite a €9 million one-time investment in 2026 for workplace conversion, the payback period is less than one year. After that, it’s pure savings every year.
Break it down per user and you get €250 saved annually across 60,000 civil servants. Meanwhile, France’s Gendarmerie achieved similar results with their GendBuntu migration—€2 million in annual savings and a 40% reduction in total cost of ownership across 103,000 Linux workstations. Therefore, the cost case for open source at this scale isn’t theoretical anymore. It’s proven.
Digital Sovereignty Drives the Politics
But this isn’t just about saving money. Digitalization Minister Dirk Schrödter frames the migration as “regaining control” of government data and reducing dependence on foreign technology providers. Indeed, post-Snowden, post-CLOUD Act, European governments want their data under their own control—not sitting in US data centers subject to American legal reach.
The political backing matters here. This migration has support from both Schrödter’s conservative CDU party and the Greens—a coalition that values digital sovereignty and long-term cost savings. Importantly, that bipartisan support is critical for surviving government changes, because history shows these migrations can be reversed when new administrations take power.
The Munich Shadow: Can This Migration Survive Politics?
Munich migrated to Linux in 2004, then reverted to Windows in 2017 after a political change. That failure looms large over every government open source project in Germany. The Hacker News community is skeptical: “We have gotten multiple efforts in Germany that have been rolled back after a new administration takes over,” one commenter noted.
Schleswig-Holstein has better odds than Munich did. The coalition support and digital sovereignty framing go beyond simple cost savings—they’re building a political narrative that can survive leadership changes. Nevertheless, challenges exist. Minister Schrödter has acknowledged “downtime and delays in email traffic” during migration. Opposition politician Kianusch Stender points out that “far fewer than 80 percent of employees can now work with them properly” despite 80% LibreOffice deployment. Training gaps and user resistance are real.
The question isn’t whether open source CAN replace Microsoft at this scale—France’s Gendarmerie already proved that. Rather, the question is whether Schleswig-Holstein’s political leadership will maintain support through implementation difficulties and user complaints. That’s where Munich failed.
France Proves It Can Work Long-Term
France’s National Gendarmerie has run 103,000 Linux workstations since 2004—20+ years without reverting to Windows. Their GendBuntu deployment reached 97% adoption as of June 2024, with a 40% TCO reduction and €2 million in annual savings. Unlike Munich, France stuck with Linux through multiple government changes and administrations.
This matters because it shows government open source migrations aren’t inherently doomed. They require sustained political will, realistic expectations about challenges, and adequate training investment. France had all three. Munich had the first wave of enthusiasm but lost political support when implementation got difficult. Ultimately, Schleswig-Holstein’s success or failure will come down to which path they follow.
Key Takeaways
- Largest EU government open source migration since France, with 60,000 users and 40,000 email accounts transitioned
- €15 million in annual savings with less than one year payback period
- Digital sovereignty framing helps build political support beyond just cost savings
- The realistic model is 80% open source, 20% Microsoft for specialized applications
- Success depends on sustained political will—Munich’s reversal shows migrations can fail after government changes
- France’s 20+ years with 103,000 Linux workstations proves long-term viability is possible
