Send Mail with ActionMailer using Postfix and Openssl through SMTP

If you want to send Email with ActionMailer through smtp under postfix and openssl, and if you have the time out error when you try this,
you have to set :tls option true.

config.action_mailer.delivery_method = :smtp
config.action_mailer.raise_delivery_errors = true
config.action_mailer.smtp_settings = {
:address => 'sample.com',
:port => 465,
:domain => 'sample.com',
:user_name => 'info@sample.com',
:password => 'xxxxx',
:authentication => :plain,
:tls  => true,
:enable_starttls_auto => true,
:openssl_verify_mode =>  'none'
}

This option hasn’t mentioned in the reference of rails, I was really confused…