Self hosted email continues to steeply decline

Self-hosted email among the internet's top million domains has declined sharply from 44.6% in 2016 to 22.4% in 2026, with Google Workspace and Microsoft 365 now handling inbound mail for 38.6% of these domains combined. This consolidation around two major providers raises resilience concerns, as outages or policy changes at either company could simultaneously impact a significant portion of the internet's email infrastructure.