Send a mail from Jenkins in Groovy Script Console

sendMail.groovy

import javax.mail.Session
import javax.mail.Message
import javax.mail.Transport
import javax.mail.internet.MimeMessage
import javax.mail.internet.InternetAddress


def descriptor = Jenkins.instance.getDescriptor("hudson.tasks.Mailer")

Session session = descriptor.createSession();
MimeMessage msg = new MimeMessage(session);

InternetAddress fromAddress = new InternetAddress(descriptor.getAdminAddress());

msg.setFrom(fromAddress)

msg.setRecipients(MimeMessage.RecipientType.TO, (InternetAddress[]) [new InternetAddress('[email protected]')].toArray());

String charset = descriptor.getCharset();
msg.setSubject("Test", charset);
msg.setText("Hello from Jenkins!", charset)

Transport transporter = session.getTransport("smtp");
transporter.connect();
transporter.send(msg);

When i am using this script direct from execute system groovy command or from script console it works!
But when i put it to Config File Management and use this groovy file on job, it fails.