Follow the below instructions to have your Redmine application send email using TLS through Gmail. As long as you have a Gmail account you will be able to send mail through smtp.gmail.com.
- Install TLS: First install TLS for the Redmine project. Login to the server with the user that runs Redmine and issue the below command from the Redmine project root directory to install TLS.
./script/plugin install http://svn.douglasfshearer.com/rails/plugins/action_mailer_optional_tls