ActionMailer not send and not generate errors

I have insert in envirmonment.rb

ActionMailer::Base.delivery_method= :sendmail

and i have created a mailer model:

class MyMailer < ActionMailer::Base
  def mail_authentication(user)
    from "parlacon@nerto.it"
    recipients user.mail
    subject "| NERTO | Conferma Registrazione"
    body :user => user
  end
end

with his template

For sending a letter i have insert in a controller this:
MyMailer.deliver_mail_authentication(@user)

but the mail don't is sent.
In the console there are no errors.

Why?
Where is the problem?

i try also with:
ActionMailer::Base.smtp_settings = {
  :address => "smtp.nerto.it",
  :port => 25,
  :user_name => "parlacon@nerto.it",
  :domain => "www.nerto.it",
  :password => "*****",
  :authentication => :plain
}

but it the same thing.
Thanks