Message: Failure sending mail. Source: System HelpLink:

NET.addAssembly('System.Net')
import System.Net.Mail.*;

mySmtpClient = SmtpClient('mail.google.com');
mySmtpClient.UseDefaultCredentials = false;
mySmtpClient.Credentials = System.Net.NetworkCredential('[e-mail]', '****');

from = MailAddress('.....com');
to = MailAddress('.....com');

myMail = MailMessage(from, to);
myMail.Subject = ['Test message: ' datestr(now)];
myMail.SubjectEncoding = System.Text.Encoding.UTF8;
myMail.Body = '<b>Test Mail</b><br>using <b>HTML</b>';
myMail.BodyEncoding = System.Text.Encoding.UTF8;
myMail.IsBodyHtml = true;
mySmtpClient.Send(myMail)