Forum: RForum Registration mail is not sent

I am trying to run my site on rforum. All work fine but emails are never
sent neither at registration nor restore password.

This is the part of my default_site.rb:
    require 'default_site'
    ActionMailer::Base.delivery_method = :smtp
    ActionMailer::Base.server_settings = {
      :address        => 'mail.domain.com', # replace with your SMTP
server
      :port           => 25, # replace with your SMTP server's port
      :domain         => 'domain.com', # replace with your HELO domain
      :user_name      => 'contact@domain.com', # set if your SMTP server
requires authentication
      :password       => 'password', # set if your SMTP server requires
authentication
      :authentication => true  # set to true if your SMTP server
requires authentication
      }