Integrate MailAdx with Campaign Monitor newsletters
Campaign Monitor supports custom HTML email sections. Add MailAdx's open-time ad tag to your Campaign Monitor templates using the subscriber personalization variable for email hashing.
Why add MailAdx to Campaign Monitor?
How to integrate MailAdx with Campaign Monitor
- 1
Create your MailAdx publisher account
Sign up and create an ad placement in the Publisher Portal.
- 2
Add a custom HTML section to your Campaign Monitor template
In Campaign Monitor's template builder, add a custom HTML block. Campaign Monitor uses the syntax [personalization tag] for contact properties.
- 3
Store and reference the email hash
Add a custom field for the SHA-256 email hash in Campaign Monitor. Import or update subscriber records with the hash value. Reference it in your HTML block.
- 4
Test and activate
Send a test email and verify the ad loads on open.
Campaign Monitor editor tips
Campaign Monitor's template builder has a 'Custom HTML' section. Use [email_hash_field] personalization syntax — import the SHA-256 hash via CSV update or API before your first ad-supported send.
<!-- MailAdx ad tag — decision runs 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=600&h=100"
width="600" height="100" alt="" />
</a>
<!-- Replace {{EMAIL_SHA256}} with your ESP's email hash merge tag -->Campaign Monitor + MailAdx: common questions
How does billing work when I send through Campaign Monitor?
You pay Campaign Monitor for email delivery as usual. MailAdx charges only when a subscriber opens and the ad image is requested — not when Campaign Monitor sends the email. A 10,000-recipient send with a 35% open rate generates roughly 3,500 billable impressions, not 10,000.
Can I use multiple ad placements in one Campaign Monitor template?
Yes. Create separate ad units in MailAdx (e.g., header, mid-roll, footer) and paste each tag in a different HTML block. Each placement has its own floor CPM and reporting in the Publisher Portal.
Does the Campaign Monitor integration work on mobile email clients?
Yes. MailAdx serves standard HTML image tags that render in Gmail iOS/Android, Apple Mail, Yahoo, and Outlook mobile. No JavaScript runs inside the inbox — the ad is a plain image request at open time.
Billing with Campaign Monitor
MailAdx bills publishers a flat platform fee per impression served — typically $0.30–$0.50 CPM — regardless of which ESP you use. Your Campaign Monitor subscription fee is separate; MailAdx does not charge per send or per subscriber. Advertisers pay you directly (or via programmatic demand) above the platform fee. Top up credits in the Publisher Portal before going live; impressions pause gracefully when credits reach zero.
Troubleshooting Campaign Monitor + MailAdx
Ad image shows as broken or blank
Confirm the email-hash merge field substitutes in a real Campaign Monitor test send — not just the editor preview. An empty hash causes MailAdx to skip the auction. Re-send a test to yourself, view the raw HTML source, and verify the eh= parameter is populated.
Impressions not appearing in Publisher Portal
Open the test email in a client that loads remote images (Gmail web, Apple Mail with images enabled). Some corporate Outlook configs block external images by default. Wait 60 seconds and refresh the portal — reporting is near-real-time.
Merge field syntax error in template
Each ESP uses different personalization syntax. Double-check you replaced {{EMAIL_SHA256}} in the MailAdx tag with Campaign Monitor's exact variable from the setup steps above. A typo in the merge tag will break the URL at open time.
Related resources
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