The Email Retainer Margin Curve: Why Bundling Beats Sending

Email platform fees are too small to carry a retainer alone, so agencies that sell sends as a standalone service cap their own revenue at the tool's price point. The margin lives one layer up: list growth, segmentation logic, creative, and lifecycle design bundled into one engagement. Agencies that bundle capture 3-5x the monthly value of a send-only contract on the same client list.