Luntbuild dealing with SMTP response 554

In our environment Luntbuild uses email as feedback mechanism for our continuous integration process. Luntbuild was configured to send an email in the build fails or succeeds including detail of build and release process. No emails were sent today, despite the fact that developers were actively working on the new project. In the Luntbuild's build log file I found the following lines

[Thread-472] INFO - Triggering step "Notify".
[Thread-472] INFO - Checking necessary condition of step "Notify".
[Thread-472] INFO - Condition satisfied, running step "Notify".
[Thread-472] INFO - Send build notification via email to: realias@foobar.com
[Thread-472] INFO - Sending email: Build of "SVN YYY build XXX" is successful
[Thread-472] WARN - Failed to send email
[Thread-472] ERROR - org.apache.tools.ant.BuildException(Problem while sending mime mail:) Cause: javax.mail.MessagingException(Could not connect to SMTP host: SMTP_SERVER_NAME, port: 25, response: 554)
[Thread-472] INFO - Step "Notify" is successful.

Been there done that. Somehow network people again removed the IP address of machine on which Luntbuild is installed from the list that the SMTP server will allow relaying from. Just to confirm my suspicion I logged in to Windows box where Luntbuild (Quickbuild) installed and tried to connect to SMTP server with this command 'telnet SMTP_SERVER_NAME 25' and got response '554 Blocked. Internal Relay Attempt From An Untrusted Host. Connection to host lost'. I have one more help ticket ticket to submit.