Clean an imported list before your first send

Klaviyo's own list-cleaning tools help with syntax but can't tell you whether nosuch@gmail.com actually exists. Securify runs a real SMTP probe on every address, plus a disposable-domain check, so you know before the first newsletter which rows are a liability.

1. 1

   In Klaviyo, import the list as usual

   Left sidebar → Audience → Lists & segments → click Create list / segment (top-right) → Create list. Give it a clear name — the Securify dashboard shows Klaviyo list names verbatim.
2. 2

   Open the Securify dashboard and click Validate on that list

   We pull every profile's email, chunk into batches of 5,000, and write the verdict back as four securify_* profile properties.
3. 3

   Create a clean segment in Klaviyo

   Left sidebar → Audience → Lists & segments → click Create segment (top-right). The Segment builder page opens. Set a name, then in the conditions area pick Properties about someone → securify_status equals deliverable. Click Create segment top-right. Target your first send at this segment instead of the raw imported list — one condition covers everything Securify thinks is safe to mail.
4. 4

   Park the rest

   Keep the original list — don't delete profiles. Klaviyo charges by profile, but undeliverables can still re-engage later if they confirm a live address, so parking (segment exclusion) is safer than deletion.

Most imported lists come back with 5–25% of the addresses flagged undeliverable or disposable. Sending only to the clean subset will cut your bounce rate below Gmail and Apple's 2% warning threshold on the first campaign.