Connecting MailAdx to Mailchimp
Mailchimp is one of the most widely used email service providers among newsletter publishers. Integrating MailAdx with Mailchimp uses open-time ad serving: paste an ad tag in your template, add an email-hash merge field, and MailAdx runs the waterfall when subscribers open your email. No webhooks or pre-send API calls required.
Prerequisites
Before starting, you'll need: a MailAdx account with at least one configured ad unit, a Mailchimp account, and access to your email template (Custom HTML block in the drag-and-drop editor works fine).
Step 1: Add the EMAIL_SHA256 merge field
In Mailchimp, go to Audience → Manage Contacts → Settings → Audience fields and *|MERGE|* tags. Add a Text field with merge tag EMAIL_SHA256. Populate it with the SHA-256 hex hash of each subscriber's lowercase email before sending.
Step 2: Copy your ad tag from MailAdx
In the MailAdx Dashboard, go to Ad Units and copy the ad tag for your placement. Replace YOUR_PUB_ID and YOUR_PLACEMENT_KEY with your values from the dashboard.
Step 3: Paste into your Mailchimp template
Add a Custom HTML block where the ad should appear and paste the ad tag. Use *|EMAIL_SHA256|* as the merge tag in the URL parameters. Mailchimp substitutes the hash at send; MailAdx runs the auction when the subscriber opens.
Step 4: Test and verify
Send a test campaign to yourself. Open the email — the ad image should load. Check Dashboard → Publisher Portal to confirm the impression was recorded. See the full guide at Mailchimp integration docs.
Conclusion
The Mailchimp–MailAdx integration typically takes under two hours. Once live, every open triggers a fresh real-time auction with no ongoing maintenance. See all ESP integration guides or book a demo for hands-on setup assistance.