Verify your Klaviyo email list before you send

The workflow

1. In Klaviyo, go to Audience > Lists & segments, open the list or segment, then Manage list (or Manage segment) > Export list to CSV and pick the properties to include. To cover every profile, build a segment of everyone first.
2. Upload the CSV on the verify page, signed in; the first 100 checks are free. The email column is found by its header or contents and every other column is kept.
3. When the job finishes, download the valid, risky and invalid files. Each keeps all of your original columns.
4. Pause any flow triggered by the list you will import into, or the import can start a welcome series for existing profiles.
5. Go to Audience > Lists & segments, open the list, then Manage list > Import contacts, upload the valid file and map each column. Klaviyo wants the first column to be the email, labelled Email or Email Address, and the file under 50 MB.
6. Keep the invalid file out of the subscriber import, as Klaviyo advises for bounced addresses, and use Klaviyo's suppression import for it so those profiles stop receiving mail. Then check the list's Imports tab for skipped rows.

Columns to map

• Email (or Email Address) as the first column; Klaviyo reads it as the profile identifier.
• Leave consent and consent-timestamp columns out of the file if you only want to update properties, so subscription status does not change.
• Do not map the SimpleVerifier result column into a consent field. Map it to a new custom property such as email_status if you want to segment on it.

What to do with risky and catch-all results

Risky profiles are mostly catch-all domains. Keep them out of your biggest campaigns: make a segment on the email_status property and send to it separately in a smaller batch, then watch the bounce rate before widening. Role addresses (info@, sales@) usually engage less, so exclude them from engagement-based flows.

What people use it for

• Clean a list before a Black Friday or product-launch send, when one high-volume campaign can damage the sender reputation.
• Verify an imported list from a previous ESP before the first Klaviyo campaign.
• Find the invalid profiles that inflate your active-profile count, which Klaviyo pricing follows.

Using the result

Each address comes back valid (the mail server confirmed the mailbox), risky (delivery could not be confirmed: a catch-all domain, a role address such as info@, or a provider that hides mailbox status) or invalid (it will bounce, or it is a throwaway address).

Full endpoint reference, error codes and an OpenAPI file are in the API docs. For lists of thousands of addresses, upload a CSV on the verify page instead.

Comparing tools? See email verifiers for Klaviyo compared, with prices checked on each vendor’s site.

Common questions

Which plans include API access for Klaviyo?

API access comes with Pro, Business and Agency, listed on the pricing page; Starter covers CSV verification only. A key on a plan without API access gets a 402 that says so. Each key can make 120 calls a minute.

Is there a SimpleVerifier app for Klaviyo?

No. There is no Klaviyo connector or marketplace listing; the CSV export and re-import above is the supported route.

Will verifying change who is subscribed?

Not by itself. Nothing in Klaviyo changes until you import a file, and leaving consent columns out of that file keeps every subscription status as it is.