Due to the volatile nature of the business world (people getting hired, fired, retiring, switching jobs, etc), there will occasionally be email addresses that are expired or incorrect at the time of your export as it has been changed or rendered void within the past 90 days (Since we refresh our database every 90 days)
We can say with confidence that at minimum, 94% of the emails contained within our database are properly verified and will be successfully sent. While we are continuing to improve our process to get this metric to a higher percentage, we cannot 100% guarantee at this time that every email address will be successfully delivered.
Also at times, our emails might not be the culprit. Deliverability also depends on your email copy, domain authority and spam traps that your domain is on.
For more information regarding email delivery, please read our blog post on the subject.