Does anyone has this problem where email lists from opt-in, rarely adding to Klaviyo? Only 10 out of our hundreds being added, on different time frame which has no relation to each other.
Or on broader problem, which platform do you best use for email flow?
Hi @Long_Nguyen ,
Could you please check if your Double Optin is off?
If you have any further questions please reach out Support.
Thanks man.
I got single opt-in saved, & Full access account. The sending seems a bit glitchy still.
Hey @Long_Nguyen 
Glad to hear you’ve got Single Opt-In enabled and Full Access set up — that’s a good start!
If Klaviyo is still inconsistently receiving leads, here are a few possible reasons you might want to check:
Script loading delays – If your opt-in form is loaded dynamically (after page load), there could be timing issues. Wrapping Klaviyo integration in DOMContentLoaded or setTimeout might help in custom cases.
Klaviyo suppression list – Sometimes contacts get suppressed due to bounced emails, unsubscribes, or policy flags — so Klaviyo silently rejects them. You can review this in the “Profiles” section.
Rate limiting or throttling – On rare occasions, especially during traffic spikes, Klaviyo may throttle incoming requests. Their API dashboard might show errors if this is the case.
If none of these seem to be the issue, try running a test opt-in with browser dev tools open (Network tab) to monitor whether the request to Klaviyo is being sent properly and if there’s any error response.
