<Resource name="mail/GmailSMTPServer"
    auth="Container"
    type="javax.mail.Session"
    mail.smtp.host="smtp.gmail.com"
    mail.smtp.port="465"
    mail.smtp.auth="true"
    mail.smtp.user="yourEmailAddress@gmail.com"
    password="yourPassword"
    mail.smtp.starttls.enable="true"
    mail.transport.protocol="smtps"
    mail.smtp.socketFactory.class="javax.net.ssl.SSLSocketFactory"
/>