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 => ‘[email protected]’,
: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:inauth_login’
c:/ruby/lib/ruby/1.8/net/smtp.rb:686:in critical' c:/ruby/lib/ruby/1.8/net/smtp.rb:581:inauth_login’
c:/ruby/lib/ruby/1.8/net/smtp.rb:571:in __send__' c:/ruby/lib/ruby/1.8/net/smtp.rb:571:inauthenticate’
c:/ruby/lib/ruby/1.8/net/smtp.rb:411:in do_start' c:/ruby/lib/ruby/1.8/net/smtp.rb:378:instart’
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:inperform_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:indeliver!’
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:insendmail’

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