Net::SMTPSyntaxError

Hey guys, I want to send an email via ROR and I have put this code at the very end in the config/environment.rb file-

ActionMailer::Base.delivery_method = :smtp ActionMailer::Base.perform_deliveries = true ActionMailer::Base.logger = nil ActionMailer::Base.raise_delivery_errors = true ActionMailer::Base.smtp_settings = {   :address => "[my smtp server]",   :port => 25,   :domain => '[my domain],   :authentication => :plain,   :user_name => 'do-not-reply@example.com',   :password => '[my password]'     }

but when i click on send mail button, it shows following error:

Net::SMTPSyntaxError in MailingController#sendmail

502 unimplemented (#5.5.1)

RAILS_ROOT: C:/work/2phone Application Trace | Framework Trace | Full Trace

c:/ruby/lib/ruby/1.8/net/smtp.rb:680:in `check_response' c:/ruby/lib/ruby/1.8/net/smtp.rb:582:in `auth_login' c:/ruby/lib/ruby/1.8/net/smtp.rb:686:in `critical' c:/ruby/lib/ruby/1.8/net/smtp.rb:581:in `auth_login' c:/ruby/lib/ruby/1.8/net/smtp.rb:571:in `__send__' c:/ruby/lib/ruby/1.8/net/smtp.rb:571:in `authenticate' c:/ruby/lib/ruby/1.8/net/smtp.rb:411:in `do_start' c:/ruby/lib/ruby/1.8/net/smtp.rb:378:in `start' c:/ruby/lib/ruby/1.8/net/smtp.rb:316:in `start' c:/ruby/lib/ruby/gems/1.8/gems/actionmailer-2.0.2/lib/action_mailer/base.rb:586:in `perform_delivery_smtp' c:/ruby/lib/ruby/gems/1.8/gems/actionmailer-2.0.2/lib/action_mailer/base.rb:469:in `__send__' c:/ruby/lib/ruby/gems/1.8/gems/actionmailer-2.0.2/lib/action_mailer/base.rb:469:in `deliver!' c:/ruby/lib/ruby/gems/1.8/gems/actionmailer-2.0.2/lib/action_mailer/base.rb:352:in `method_missing' app/controllers/mailing_controller.rb:8:in `sendmail'

Please help me out from this problem, i have got stuck due to this

Thanks

Please also tell me the requirements for sending mail, if i am missing something. any gems, settings or ...

Thanks