Not able to send mails using Gmail SMTP server

See this article (similar on AEM 6 - if any difference):

http://therealcq.blogspot.ca/2013/01/setting-up-gmail-as-your-smtp-server-in.html

Also make sure that you specify your SMTP user name and password. 

Thanks for the reply.

I have done the similar configurations as given in the link , but still I am getting the below error.

Caused by: javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 465;
  nested exception is:
    java.net.ConnectException: Connection timed out: connect
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1961)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:654)
    at javax.mail.Service.connect(Service.java:317)
    at javax.mail.Service.connect(Service.java:176)
    at javax.mail.Service.connect(Service.java:125)
    at javax.mail.Transport.send0(Transport.java:253)
    at javax.mail.Transport.send(Transport.java:124)
    at org.apache.commons.mail.Email.sendMimeMessage(Email.java:1232)
    ... 132 more
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.connect(Unknown Source)
    at sun.security.ssl.BaseSSLSocketImpl.connect(Unknown Source)
    at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:299)
    at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:208)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1927)
    ... 139 more

Please provide the solution for the same.

Thanks

Try building a custom eamil service within AEM:

https://helpx.adobe.com/experience-manager/using/creating-custom-cq-email-services.html

This article walks you through how to do that. Then try connecting to the same SMTP server. Let us know what happens.