[BlueOnyx:06674] Stoping backscatter from majordomo ?

[bluequartz at ozin.com]

We have majordomo turned off on our server.
Postmaster keeps replying to mail to majordomo@ and is thus guilty of backscatter.
How do I stop it replying?

Thanks for your help

Below is an example:

=========================================================

Date: Wed, 2 Feb 2011 19:54:07 GMT
From: Mail Delivery Subsystem <MAILER-DAEMON>
To: margheritaeroycemf at flowergallery.com
Subject: Returned mail: see transcript for details

The original message was received at Wed, 2 Feb 2011 19:54:04 GMT
from [91.73.127.58]

   ----- The following addresses had permanent fatal errors -----
"|/usr/local/majordomo/wrapper majordomo -C /usr/local/majordomo/sites/site4/majordomo.cf"
    (reason: Service unavailable)
    (expanded from: <majordomo at mydomain.org>)

   ----- Transcript of session follows -----
smrsh: "wrapper" not available for sendmail programs (stat failed)
554 5.0.0 Service unavailable


    [ Part 3.2: "Delivery Status" ]

Reporting-MTA: dns; t6.tec1.net
Received-From-MTA: DNS; [91.73.127.58]
Arrival-Date: Wed, 2 Feb 2011 19:54:04 GMT

Final-Recipient: RFC822; majordomo at mydomain.org
X-Actual-Recipient: X-Unix; |/usr/local/majordomo/wrapper majordomo -C
/usr/local/majordomo/sites/site4/majordomo.cf
Action: failed
Status: 5.5.0
Diagnostic-Code: X-Unix; 69
Last-Attempt-Date: Wed, 2 Feb 2011 19:54:06 GMT