Cohort for Email-Security Analysis: 2,834 Businesses by County & Employee Size

This table defines the business cohort (n = 2,834) we used for the DNS analysis of SPF and DMARC. Each count represents organisations grouped by county and employee number; from this list we identified their domains and then performed authoritative DNS lookups to capture SPF and DMARC. The distribution shows a predominantly SME-heavy landscape across most counties, with larger employers concentrated in Dublin and Cork, context that informs subsequent adoption and enforcement rates.