Building a custom ESP send pipeline with MailAdx
Not every newsletter publisher uses a commercial ESP. Many larger operations run custom send infrastructure — homegrown email builders, custom SMTP pipelines, or internally developed templating systems. MailAdx integrates with custom pipelines via the same open-time ad tag pattern used by Mailchimp and Klaviyo.
The recommended integration pattern
At the point in your pipeline where you render the final HTML email for each subscriber, substitute each subscriber's SHA-256 email hash into the MailAdx ad tag URLs. Paste the ad tag once in your template; your renderer replaces the hash placeholder per subscriber at send. When the subscriber opens the email, MailAdx runs the waterfall and returns the winning creative.
Ad tag structure
<a href="https://mailadx.com/api/v1/serving/click?pub=YOUR_PUB_ID&pk=YOUR_PLACEMENT_KEY&eh={{EMAIL_SHA256}}"
target="_blank" rel="noopener">
<img src="https://mailadx.com/api/v1/serving/display?pub=YOUR_PUB_ID&pk=YOUR_PLACEMENT_KEY&eh={{EMAIL_SHA256}}&w=728&h=90"
width="728" height="90" border="0" alt="" style="display:block;"/>
</a>Replace {{EMAIL_SHA256}} with your template engine's variable for the subscriber hash. Compute it as sha256(email.lower()) in hex.
Advanced: pre-render via Decision API
If your pipeline requires baking creative HTML into the email body before send (rather than a dynamic image URL), you can optionally call GET /api/v1/serving/decision per subscriber and inject the returned emailHtml. This is more complex and loses open-time pacing benefits — most custom pipelines should use the ad tag pattern above. See the Advanced section in the API reference.
Conclusion
Custom pipeline integration with MailAdx is straightforward: hash substitution + ad tag paste. Visit the developer hub for display URL parameters, or book a demo for architecture review.