postfix and rails (ubuntu)

I've got postfix up and running on my rails system (unsure if it's
correct), but Rails doesn't seem to talk to it at all.

I've setup:

ActionMailer::Base.delivery_method = :sendmail
ActionMailer::Base.smtp_settings = {
  :address => 'localhost',
  :domain => 'www.mywebsite.com',
  :port => 25
}

But it doesn't work. Which log files should I check and/or how do I
fix this? I'm running Ubuntu and the latest stable rails version.

instead of :sendmail, try :smtp

To answer your questions specifically.

Check your app logs tail -f log/development.log
Check your mail server's logs in /var/log/smtp.log? /var/log/
postfix.log ?

thank you those fixed it!