Action Mailer does not raise exceptions with Rails 2.3.2

Hi,
I am trying to have ActionMailer raise exceptions with rails 2.3.2 but
it does not.

In development.rd I have
config.action_mailer.raise_delivery_errors = true

I tought it was due to a misconfiguration, so I modified
deliver! in /usr/local/lib/ruby/gems/1.8/gems/actionmailer-2.3.2/lib/
action_mailer/base.rb
to always raise any exceptions, but still no exceptions are raised.

How to repeat:
- create a new rails app with 2.3.2
- script/generate a new mailer with one method
- configure development.rb: config.action_mailer.raise_delivery_errors
= true
- make sure that one method should raise an exception (i.e. wrong
address)
- call the method and...
no exception is raised.

Same thing on 2.2.2 raises the exception.

Anyone with this problem?

I'm running on OSX with either ruby 1.8.7 or 1.9.2dev and rails
2.3.2. Forcing a mail error with

config.action_mailer.raise_delivery_errors = true

causes a long message to appear in my log that starts:

Net::SMTPAuthenticationError (535-5.7.1 Username and Password not
accepted. Learn more at
):
  /opt/local/lib/ruby/1.8/net/smtp.rb:942:in `check_auth_response'
  /opt/local/lib/ruby/1.8/net/smtp.rb:733:in `auth_plain'
  /opt/local/lib/ruby/1.8/net/smtp.rb:725:in `send'
  /opt/local/lib/ruby/1.8/net/smtp.rb:725:in `authenticate'
  /opt/local/lib/ruby/1.8/net/smtp.rb:566:in `do_start'
  /opt/local/lib/ruby/1.8/net/smtp.rb:525:in `start'
  app/models/user_observer.rb:3:in `after_create'

and goes on from there.