Hi, please contact us at [email protected] and provide us with the list of emails that bounced. In most cases, the issue is somewhere end. Because email verification is the first step of email marketing. Someone have a clean email list doesn't mean that he can start sending mess emails (it may not be your case). After checking your bounced emails, we can tell exactly what caused these bounces. You also didn't mention if you utilized our overall_score parameter or not. We will be waiting for your response. Thanks.