Abandoned Cart flow skipping ALL recipients with "Email Syntax Error" — valid addresses affected

Question

Flow: Abandoned Cart, triggered by Checkout Started (Shopify integration). Email #1 is skipping every recipient with "Email Syntax Error" — including clean addresses. Smart Sending is OFF. We disconnected and reconnected the Shopify integration today — issue persists. Real customers are being lost. Store: ekoneu.com. Klaviyo plan: Free.

EKO26 · Answer

---Additional details:Issue started: approximately September 25, 2026Smart Sending:OFFConsent at checkout:"Email me with news and offers" checkbox — checked by all affected usersClean addresses being skipped:onyeka.adegoke@gmail.com(standard Gmail, no special characters)Shopify integration wasdisconnected and reconnectedSeptember 29 — issue persistsAll 17+ skipped recipients show identical reason: "Email Syntax Error"Flow trigger: Checkout Started (Shopify native integration)No flow-level filters set[Attach screenshot of Recipient Activity showing "Skipped: Email Syntax Error (17)"]Skipped: Email Syntax Erroronyeka.adegoke@gmail.com moved from waiting to skipped now

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