TestMail.groovy

import javax.mail.internet.InternetAddress;
import com.liferay.mail.kernel.model.MailMessage;
import com.liferay.mail.kernel.service.MailServiceUtil;

// from
InternetAddress from = new InternetAddress();
from.setAddress("admin@liferay.com");

// to
InternetAddress to = new InternetAddress();
to.setAddress("klaas@gmail.com");

MailMessage mailMessage = new MailMessage(from,to,"bujsub","body body",Boolean.TRUE);
MailServiceUtil.sendEmail(mailMessage);