For popular domains like hotmail, yahoo etc., it might be fair to assume that the e-mail exists.
However, with the majority of e-mail domains, you cannot guarantee that an e-mail address is valid based only on domain verification. But, this may be the only level of verification that is available by the mail server.
Many mail servers are blocking or intentionally not responding to a SMTP (mailbox) level verification. Many SMTP servers now reverse-verify the e-mail address and/or IP, a client provides (in this case Smart Email Verifier) when communicating with the mail server. If the SMTP server finds that the e-mail address or IP does not exists or is blacklisted, it usually does not respond. In Smart Email Verifier, such a situation results in an SMTP connection timeout.
For accurate results, use a valid IP address for HELO and a valid e-mail address for the `Mail From' field. Also, make sure that you are using the latest version of Smart Email Verifier.
