ZapBounce

ZapBounce and Klaviyo

Klaviyo suppresses a profile after it hard bounces, so the check that protects your sending has to run before the profile exists. ZapBounce verifies Klaviyo data three ways: a CSV export you upload, the ZapBounce API in front of your signup form, and a Zapier step on new profiles.

Ecommerce stores feel this most. Profiles arrive from checkout, from popups and from a previous platform, and each source fails in its own way. A popup collects typos, a migration brings years of dead addresses, and checkout is usually the cleanest of the three.

A suppressed profile stays suppressed

Klaviyo tracks bounce rate, spam complaint rate and unsubscribe rate as ongoing health measures. When an address hard bounces, Klaviyo suppresses the profile on its own, and it stays that way unless you step in.

That makes a bad import hard to undo. If a real customer mistyped their address at a popup, they never receive another flow, and their order history sits on a profile nobody can reach.

Klaviyo also judges sending reputation across the whole account. One dirty import can drag down flows that have nothing to do with the list you brought in. If you're moving platforms, read verifying before a Klaviyo migration first.

How the data moves

  1. Pick the file route or the API route

    For a one-time clean, export profiles as CSV and upload the file on the bulk page. For ongoing checks, call POST /v1/verify before your code creates the profile, so nothing unverified gets in.

  2. Store the result as a custom profile property

    Use a property rather than a list membership. Klaviyo segments can read a property, and it survives any list changes you make later.

  3. Build segments on the property

    A segment where the result equals valid gives you a clean sending audience without deleting a single profile. Catch-all profiles get their own segment and their own flow.

  4. Check new profiles through Zapier

    A Zap on new Klaviyo profiles runs a ZapBounce check and writes the result back. For file jobs, poll the job status and import once it completes.

Setting it up

  1. Export profiles from Klaviyo as CSV, keeping every property column you want to keep.
  2. Upload the file, and ZapBounce returns the status, reason code and SMTP code for every address, ready to match back on email.
  3. Create a custom profile property for the result, and a date property for when you checked.
  4. Import the results back, matching on email so existing profiles update in place.
  5. Create a segment where the result equals valid, and point your main flows at it.
  6. Create a second segment for catch-all profiles, send to it on its own, and watch its bounce rate separately.

Klaviyo: common questions

Does Klaviyo verify emails?

Klaviyo acts after a send: it suppresses a profile once the address hard bounces. A ZapBounce check before import or at signup catches that dead address first, at $5 for 1,000 checks, so the profile is never suppressed.

Will verifying stop Klaviyo suppressing profiles?

It removes the addresses that would have hard bounced, which is the main cause of suppression. Complaints and unsubscribes are a separate matter that consent and content handle.

Should I delete invalid profiles or suppress them?

Suppress them. The profile carries order history worth keeping, and it's the address that stopped working, not the customer.

Does a clean list help with a Klaviyo deliverability review?

Yes, on the first thing reviewers look at, which is bounces. Sending consistency, authentication and list age matter too, and each has its own fix.

Reference

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