The Erosion of Self-Hosted Email

The landscape of internet communication is shifting toward a centralized model dominated by two tech giants, according to reporting from The Register.

Artem Berezin, a researcher at Live Direct Marketing, analyzed DNS records using snapshots from the OpenINTEL project—a collaboration between SIDN Labs, SURFnet, and the University of Twente—alongside Tranco project domain data. Berezin found that in 2016, 44.6 percent of the top million domains operated their own mail servers. By 2026, that figure dropped to 22.4 percent.

While self-hosting remains the most common method, Google Workspace and Microsoft 365 have captured a massive share of the market. Google Workspace accounts for 21.8 percent of detectable MX records, while Microsoft 365 holds 16.8 percent. Together, these two providers handle 38.6 percent of email for popular domains.

Berezin warns that this concentration creates a systemic dependency. Because email lacks a "graceful fallback," a single policy change, filtering adjustment, or outage at either company can propagate across the entire ecosystem instantly. Furthermore, the dominance of these providers creates a cycle that marginalizes independent operators. As Google and Microsoft employ filters to block messages from sources they deem untrustworthy, those using free and open-source software like Postfix struggle to get mail accepted at scale. This pressure pushes marketers and users toward the big two to ensure deliverability.

Additional vulnerabilities exist in authentication. Berezin noted that over half of DMARC records lack a valid policy or fail to enforce monitoring, despite requirements implemented by Yahoo and Google in 2024 for bulk senders.