mandrill mailer not working in Rails4

Question

I have following code snippet in development.rb

  config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.perform_deliveries = true
  config.action_mailer.raise_delivery_errors = true

  config.action_mailer.smtp_settings = {
    :address => "smtp.mandrillapp.com",
    :port => 587,
    :authentication => 'login',
    :user_name => "example@mail.com",
    :password => "xxxxxxxx",
    :enable_starttls_auto => true
  }

But in log mail is sending without any error, but I am not getting any mail in my mailbox. I tried in all possible ways but no luck. Please help me to solve this problem.