Open-time ad decisioning for email
MailAdx's ad server runs the full waterfall in real time when subscribers open your email — returning the winning creative via a dynamic image URL in under 5ms. No JavaScript, no per-subscriber API loops, no deliverability risk.
Why open-time beats send-time
Send-time decisioning charges impressions for every subscriber on your list — even the 85% who never open. Campaign pacing freezes at send time, so capped-out advertisers can still serve hours later. MailAdx's open-time approach runs a fresh auction when the subscriber opens: impressions reflect genuine exposure, budgets and frequency caps apply in real time, and advertisers pay only for emails that were actually opened.
- Impressions only for genuine opens — not wasted send-level charges
- Live pacing and frequency caps at the moment of delivery
- No per-subscriber API loop — paste ad tag once in your template
Integrate in one afternoon
Copy the ad tag from Dashboard → Ad Units and paste it into your ESP template. Add an EMAIL_SHA256 merge field so each subscriber's hash is substituted at send. When they open the email, MailAdx handles the rest. No webhooks, no send pipeline changes, no backend infrastructure required.
- Two-line HTML ad tag for Mailchimp, Klaviyo, and any ESP
- Step-by-step guides for every supported ESP
- Sandbox mode for testing before your first live send
Everything you need
All the features, none of the complexity.
Sub-5ms response time
Waterfall completes in under 5ms at open time — fast enough for every email client image fetch.
OpenRTB integration
Connect to any OpenRTB-compatible SSP or exchange as a demand source in minutes.
Waterfall prioritisation
Configure direct-sold, PMP, programmatic, and house ad tiers with custom priority rules.
Real-time fallback
Automatically fall through to the next demand tier if the highest-priority source doesn't fill.
Dynamic creative delivery
Returns winning creative via 302 redirect to image — one ad tag paste works for all subscribers.
Detailed decision logs
Every open-time decision is logged with bid prices, winning demand source, and creative metadata.
“We pasted the ad tag once and were live. Every open gets a fresh auction — pacing and caps always apply correctly.”
Power every open with real-time ad decisions
Paste one ad tag in your template. MailAdx runs the waterfall when subscribers open — accurate impressions, live pacing, no manual work.