Sending mail using goamil v2 -Taking loo long and no response

[ganeshsaptang]

How to send mails using gomail v2 with STARTTLS ? but without credentials {username and password } is it possible? I tried without using username password but its taking loo long and no response.

This is the config im passing to my Dialandsend method :
tlsConfig := &tls.Config{InsecureSkipVerify: true, ServerName: hostName}
dialer := gomail.Dialer{
Host: hostName,{smtp-relay.gmail.com }
Port: portNumInt,
TLSConfig: tlsConfig,
}

I tried with port 25 and it worked fine but for startTLS its not working and the functionality is working fine in python(using smtplib) any ideas ?