Self-hosted email is declining rapidly, with Microsoft and Google increasingly dominating how domains receive mail, according to research by Artem Berezin of business e-mail company Live Direct Marketing, published on the Internet Society blog. This matters because it concentrates control over global email delivery in the hands of two companies, meaning an outage, filtering change, or policy shift at either could disrupt communication across much of the internet, with no fallback if a message is rejected.

Berezin's analysis of DNS records, using daily snapshots from the OpenINTEL project and Tranco's list of top domains, found that the proportion of the top million domains running their own mail server fell from 44.6 percent in 2016 to 22.4 percent in 2026, and is still dropping by roughly half a percent every 30 days. Google Workspace now handles 21.8 percent of detectable mail servers and Microsoft 365 16.8 percent, meaning the two firms together manage 38.6 percent of email delivery. Berezin also warned that over half of DMARC anti-spoofing records remain unenforced despite 2024 mandates from Google and Yahoo, and that smaller mail operators increasingly struggle with deliverability in a system tuned to favour the two giants.