The ad server for newsletter publishers
Whether you've already sold a sponsorship or you're starting from an empty slot, MailAdx is the ad stack underneath it — one tag in your ESP running your own direct deals, programmatic fill, and house ads. Frequency capping, creative swaps after you've hit send, and a delivery report every sponsor can verify. No revenue share on direct-sold, no marketplace lock-in.
One ad tag. Every ad you'll ever run.
Paste one tag into your ESP template, once. From then on everything runs through it — the sponsors you sell yourself, programmatic demand on the sends you haven't sold, and your own house ads in between. No copying sponsor HTML into this week's draft, no template edit every time a deal changes, and nothing to redo when you land your first direct advertiser.
- One placement handles direct, programmatic, and house ads
- Add, swap, or pause an advertiser without touching your template
- Works inside Beehiiv, Mailchimp, Klaviyo and 15 more ESPs
A delivery report your sponsors don't have to take on faith
When a sponsorship ends, you owe that advertiser proof it ran. Most publishers send a screenshot and an estimated open rate. The MailAdx Publisher Portal gives you a real, timestamped, open-time delivery report for every placement — impressions, opens, clicks, and revenue, broken down by sponsor and send. Forward it directly or export the CSV.
- Real, open-time-verified delivery numbers — not estimates
- Per-sponsor, per-send breakdown ready to forward
- CSV export for your own invoicing and reconciliation
Everything you need
All the features, none of the complexity.
One tag, every demand type
Direct-sold, programmatic, and house ads all run through a single placement — set it up once, change what fills it whenever.
House ads from day one
No advertisers yet? Run your own paid tier, referral program, or product promos in the slot until you sell it.
Swap creative after you've sent
A sponsor changes their offer mid-flight? Update the creative once — every future open serves the new version.
Delivery reports sponsors can verify
Real impressions, opens, and clicks — timestamped at open time, not estimated from a send count.
Frequency capping, per subscriber
Cap how often the same reader sees an advertiser across sends — evaluated at open time, not batched at send.
0% on direct-sold
Pay a flat per-impression serving fee — $0.30–$0.50 per 1,000 — on sponsors you sell yourself. Keep 100% of what your advertisers pay you.
Put an ad slot in your next send
Set up your placement in the time it takes to read this page. Run house ads in it today — and the plumbing already works the day you close your first sponsor.