Your newsletter's ad slots, filled automatically.
MailAdx fills your newsletter ad slots automatically — 94% fill rate, $4+ eCPM, works with Beehiiv, Mailchimp, Klaviyo and 22+ ESPs. No revenue share.
Works with your ESP — paste one tag, done
94%
avg. fill rate
<5ms
ad decision
22+
ESPs supported
Who it's for
Built for both sides of the market
Turn every subscriber open into ad revenue
- 94% average fill rate — no empty slots
- $4+ eCPM for engaged audiences
- One tag in your ESP, live in 30 minutes
Reach newsletter readers who actually read
- First-party email-hash audiences — no cookies, no guesswork
- Ad Journeys: sequential multi-send campaigns with branching
- Retarget engaged openers, clickers & converters across sends
Platform
One platform, every role
Publishers, advertisers, and operations teams each get purpose-built tools — unified under a single account.
Monetise every newsletter send
MailAdx SSP gives you a complete inventory management layer — define ad placements, set price floors, control which advertisers appear, and watch revenue flow automatically at every send.
- Drag-and-drop ad unit builder with live preview
- Per-placement floor prices and category blocks
- Publisher portal with real-time fill and revenue
Publisher portal — real-time fill rate, eCPM & revenue
Reach engaged newsletter readers
The MailAdx DSP lets you launch, target, and optimise email ad campaigns with precision — audience segments, creative variants, daily budget controls, and transparent delivery reporting.
- Audience targeting by topic, geo, and list size
- Multiple creative formats: image, text, sponsored sections
- Ad Journeys: sequential campaigns across sends
Advertiser dashboard — impressions, clicks, CTR & spend
Open-time intelligence, not stale send-time ads
When a subscriber opens your email, MailAdx runs the full waterfall in real time via a dynamic image URL — fresh pacing, live caps, and accurate impressions for every open.
- Sub-5ms waterfall at open time via display URL
- OpenRTB-compatible waterfall and direct-sold prioritisation
- Fallback and house ad support built in
Open-time waterfall — every open triggers a fresh auction
How it works
From setup to first ad in one afternoon
MailAdx is designed to fit into your existing workflow, not replace it.
Connect your ESP
Add an email-hash merge field and paste the MailAdx ad tag into Mailchimp, Klaviyo, Beehiiv, or any ESP template. No webhooks or per-subscriber API loops required.
Define placements & inventory
Use the Publisher Portal to create ad placements within your newsletter template. Set price floors, block lists, and creative specifications per slot.
Load demand
Add advertisers directly via the DSP dashboard, connect to OpenRTB exchanges, or negotiate private marketplace deals. MailAdx manages prioritisation automatically.
Open — ad decisions in <5ms
When a subscriber opens your email, their client fetches the ad image URL. MailAdx runs the waterfall in real time and returns the winning creative — impressions only count for genuine opens.
<!-- Step 4: Paste ad tag — decision at open time -->
<a href="https://mailadx.com/api/v1/serving/click?pub=YOUR_PUB&pk=header&eh={{EMAIL_SHA256}}"
target="_blank">
<img src="https://mailadx.com/api/v1/serving/display?pub=YOUR_PUB&pk=header&eh={{EMAIL_SHA256}}&w=728&h=90"
width="728" height="90" alt="" />
</a>
// {{EMAIL_SHA256}} = your ESP's subscriber hash merge tagHow MailAdx works
Three steps from signup to revenue — open-time decisioning means you only pay for impressions that actually happen when subscribers open your newsletter.
1. Paste one ad tag in your ESP
Create a publisher account, configure ad placements with floor CPMs and format rules, then copy the HTML ad tag from the Publisher Portal. Paste it into a custom HTML block in Beehiiv, Mailchimp, Klaviyo, or any of our 14 ESP integrations. Replace the email-hash placeholder with your ESP's merge field — SHA-256 preferred for frequency capping and GDPR-safe targeting.
2. Open-time auction on every open
When a subscriber opens your email, their client requests the dynamic image URL. MailAdx runs a sub-5ms auction across direct-sold campaigns, programmatic OpenRTB demand, and house ads. The winning creative returns as a standard HTML image — no JavaScript, no cookies, no inbox scripts. Budgets pace in real time; frequency caps apply per household hash, not per send batch.
3. Report, optimize, scale
The Publisher Portal shows impressions, eCPM, fill rate, and per-placement performance. Advertisers use the self-serve DSP to target geo, device, topic, and newsletter categories. Agencies manage multiple clients from one network account with role-based access and consolidated billing.
Built for publishers and advertisers
For publishers
Own your ad stack instead of renting space in someone else's marketplace. Set custom floor CPMs, run direct-sold campaigns alongside programmatic fill, and keep 100% of advertiser spend above the flat platform fee. No revenue share, no monthly subscription — pay only for impressions served.
- SSP inventory management with category and advertiser block lists
- Native ads rendered as composite PNGs — works in every email client
- Ad Journeys: sequential campaigns that advance as subscribers open future sends
- Works with 22+ ESPs via a single HTML tag — see integration guides
For advertisers
Reach engaged newsletter audiences with transparent pricing and real-time delivery reporting. Self-serve campaign creation — no IO, no minimum contract. Target by geography, device, newsletter topic, and placement. Pay only when your ads serve on genuine opens.
- DSP with geo, device, and topic targeting across 500+ newsletters
- Real-time dashboard: impressions, clicks, CTR, spend pacing
- $100 minimum credit top-up — no card required at signup
- OpenRTB-compatible for programmatic buyers and agencies
Platform at a glance
94%
Average fill rate across active publishers
$4+
Typical publisher eCPM on monetized placements
22+
ESP integrations with step-by-step guides
<5ms
Open-time auction decision latency (p50)
Why open-time beats send-time
Traditional email ad networks charge per send — every recipient in your list counts as an impression whether they open or not. Industry benchmarks put newsletter open rates between 35–45%, meaning send-time models overcharge advertisers and underpay publishers who actually deliver engaged readers.
MailAdx's open-time model aligns incentives: advertisers pay for verified opens, publishers earn more per engaged reader, and frequency caps work because the hash is evaluated at the moment of open — not batched at send time when Apple Mail Privacy Protection and Gmail prefetch can distort counts.
The architecture is privacy-first by design: SHA-256 hashed emails in ad URLs, no third-party cookies, no JavaScript in the inbox, and GDPR/CCPA compliance built into the serving path. Explore our open-time ad serving glossary entry or compare MailAdx to Paved, Beehiiv Ad Network, and LiveIntent for a full competitive picture.
Platform performance
Built to perform at every open
These numbers reflect aggregate performance across the MailAdx network — real figures, not projections.
94%
Average fill rate
Across the MailAdx publisher network
$4+
Typical publisher eCPM
For newsletters with engaged B2B audiences
<5ms
Ad decision latency
Full waterfall at email-open time
22+
ESP integrations
Mailchimp, Klaviyo, Beehiiv and more
FAQ
Frequently asked questions
Everything you need to know about newsletter advertising with MailAdx.
More questions? Browse the help center or contact us directly.
Start monetising your newsletter today
Join 150+ newsletter operators using MailAdx to run a full ad stack — without the complexity.