Not always. We have an average of 98% accuracy. Some email providers make it hard to check if the email really exists. So, sometimes the email will return as valid but maybe it's not. The bad emails are bad for sure. And some may return as unclear.
1. We check the basics first, like email syntax and if the e-mail domain is real; 2. If the email passes the step 1, we check if the domain has at least one MX server and if the email server is operational; 3. If the email passes the step 2, we check if the email account exists in the email provider.
Inboxpath Email Checker
Depending on the e-mail provider, the verification process can take some time.