Sponsorship CPM

Sponsorship CPM is the effective cost-per-mille calculated from a flat-fee newsletter sponsorship. If a publisher charges $500 for an exclusive sponsor slot and the newsletter has 50,000 subscribers with a 40% open rate, the effective CPM is: ($500 ÷ (50,000 × 0.40 / 1,000)) = $25 CPM. Sponsorship CPMs for premium B2B newsletters often range from $20–$60+, significantly higher than programmatic rates. However, flat-fee sponsorships are paid per send (not per open), which means the publisher guarantees delivery but the advertiser pays for unread sends. Publishers moving to open-time ad serving charge per impression (per genuine open) — which is more transparent for advertisers and more accurate for publishers.