A map showing the providers behind official emails of 2,100 Swiss municipalities

This is a map visualizing which email provider each municipal domain uses, covering about 2,100 municipalities in Switzerland.

• Results per municipality are grouped by jurisdiction.
• Determination used 11 signals, including DNS records, SMTP banners, ASN lookups, and public Microsoft API endpoint.
• Each provider is classified using confidence scoring.
• It notes that DNS records only indicate mail routing and authorized senders, and do not directly mean where the actual data is stored.
• The code and data are published on GitHub, and an issue tracker is available for reporting errors.

The core message is digital sovereignty. Since US-based providers can be subject to the US CLOUD Act, the significance lies in exposing the current distribution of public institutions' email infrastructure through public data.