Als je vraag is of het emailadres valide is, dan is het antwoord: ja
Log:
MX record about engineer.com exists.
Connection succeeded to mx0.gmx.com SMTP.
220 mx0.gmx.com GMX Mailservices ESMTP {mx-us017}
> HELO verify-email.org
250 mx0.gmx.com GMX Mailservices {mx-us017}
> MAIL FROM:
=250 2.1.0 ok {mx-us017}
> RCPT TO:
=250 2.1.5 ok {mx-us017}