Redmine

We are attempting to configure Redmine to send out emails via our Qmail server. I believe we have the email.yml configuration correct, but when we attempt to send a test email, we get this message:

An error occurred while sending mail (502 unimplemented (#5.5.1) )

The qmail server seems to be contacted by Redmine, but its logs return Status 256. Anyone using qmail? We can't find anything that tells us what Status 256 is.

Our Rails info:

About your application's environment
Ruby version 1.8.5 (x86_64-linux)
RubyGems version 1.1.1
Rails version 2.1.2
Active Record version 2.1.2
Action Pack version 2.1.2
Active Resource version 2.1.2
Action Mailer version 2.1.2
Active Support version 2.1.2
Edge Rails revision unknown
Application root /root/redmine-0.8.3
Environment development
Database adapter mysql

And here is the email.yml:

production:
delivery_method: :smtp
smtp_settings:
address: 10.0.0.12
port: 25
domain: ttmi.info
authentication: :login
user_name: "redmine@ttmi.info"
password: "------"

development:
delivery_method: :smtp
smtp_settings:
address: 10.0.0.12
port: 25
domain: ttmi.info
authentication: :login
user_name: "redmine@ttmi.info"
password: "------"

The IP address is our internal qmail server. Anyone?
Thanks!