What’s the difference between ESP-side and CRM-side data?
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Your ESP sees what happens inside the email environment. Your CRM sees what happens after someone acts on it. These two views rarely line up exactly, and that's fine once you understand why.
ESP-side data covers: deliveries, opens, clicks (through the ESP's tracking redirect), bounces, unsubscribes, and spam complaints. Everything measured by your sending platform. The ESP's click count increments the moment someone hits your redirect link. It doesn't know what happened next.
CRM-side data covers: page views after the click, form fills, purchases, deal stages, contact updates. Everything measured by your website and downstream systems. The CRM's conversion count increments when someone completes an action, not when they click an email link.
The gap between these two shows up as attribution discrepancies. Your ESP reports 1,200 clicks on a campaign. Your CRM shows 800 visits from email. Your analytics platform shows 750. These numbers will never perfectly match because they're measuring different moments in the same journey, with different tracking methods, through different attribution windows.
Which system wins? Neither. You designate one as the source of truth for each metric type. The ESP owns deliverability metrics (bounces, complaints, inbox placement). The CRM or analytics platform owns business outcome metrics (conversions, revenue, pipeline).
For a working reconciliation approach when the numbers are wildly different, see how to reconcile conflicting data sources. And for the full picture of what multi-ESP setups do to your metrics, that's worth reading before you add another platform to your stack.
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