MailAdx

MailAdx is an advertising technology platform built specifically for email newsletters, bringing ad serving, publisher inventory management, and campaign buying together. Its central product is an open-time ad server: publishers add a single tag to a supported email service provider, and MailAdx selects an ad when a subscriber opens the message rather than when it is sent. The system can combine publisher-sold sponsorships, programmatic demand, and house ads, with direct-sold revenue not subject to revenue sharing.

For publishers, MailAdx provides tools to create placements, set price floors, manage advertiser and category exclusions, and monitor fill, impressions, eCPM, and revenue. For advertisers, its self-serve demand-side platform supports campaign creation, audience targeting by factors such as geography, device, newsletter topic, and placement, plus creative options, budget controls, and delivery reporting. The platform also offers sequential Ad Journeys across newsletter sends and support for OpenRTB demand. MailAdx integrates with 18 email service providers, including Beehiiv, Mailchimp, and Klaviyo, and provides documentation and dashboards for publishers, advertisers, and operations teams.