What’s the risk of broken personalization in automations?
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Picture this: you set up a welcome automation, and thousands of subscribers get an email that starts with "Hi {First_Name}." Not their actual name. The literal placeholder text your ESP never filled in. It happens more than you'd think, and it's one of those mistakes that's impossible to un-see.
Broken personalization comes in a few different flavors. The most visible is a raw merge tag sitting in plain text, like {First_Name} or {{customer.city}} appearing word-for-word in the subject line or body. That one's jarring. But equally damaging is a blank space where the name should be, so the email just reads "Hi ," with a lonely comma. Or worse, the wrong value entirely, because a data sync pulled the wrong field and now you're calling Jamie "Premium" (the tier label that mapped to the wrong column).
The damage isn't just cosmetic. An email that shows broken personalization immediately signals that something automated went wrong. Subscribers notice. Some mark it as spam because it feels like a phishing attempt. Others lose trust in the brand, quietly. You might not see it in your open rates right away, but you'll feel it in long-term disengagement.
Most broken personalization comes down to a handful of root causes. A contact's field is empty and no fallback value was set. A data sync between your CRM and your ESP failed silently and left fields unpopulated. Or a field mapping was set up incorrectly at integration time, so the right column never got matched to the right tag. Untested edge cases do the rest.
The fix is simpler than you might expect. Set a fallback (sometimes called a default value) for every merge tag you use. Instead of just {First_Name}, write something like {First_Name | fallback: "there"} so the worst-case email reads "Hi there" instead of "Hi {First_Name}." That's not glamorous, but it's not embarrassing either.
Beyond fallbacks, always preview your automation with real subscriber data before activating it. Most ESPs like Klaviyo, ActiveCampaign, and Customer.io let you pull in an actual contact to preview exactly what they'd receive. Use that. And after a send, spot-check a sample of outgoing emails to catch any edge cases the preview missed.
One broken personalization tends to overshadow every correct one in that same email. The error is what sticks. A little prevention goes a long way here.
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