I tried to use Gmail SMTP with the following settings to send a test email but failed.

Settings:

• Enable debug [YES]
• SMTP Port [465] / [587]
• Use SSL/TLS [True]
• Username [xxx@gmail.com]
• Password [xxxxxx]

Error message:

Starting mail system...
mail.smtp.host = smtp.gmail.com
mail.smtp.starttls.enable = true
mail.smtp.port = 587
mail.from = noreply@cityu.edu.hk
mail.smtp.auth = true
username = cityuocio@gmail.com
password = *******
Mail system started.
Invalid user email '' - using server email as from address.
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "smtp.gmail.com", port 587, isSSL false
problem sending email
Permission denied: connect
at java.net.TwoStacksPlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157)