Could an admin kindly find and kill the source of these?:

---------- Forwarded message ----------
From: postmaster at pallmann dot com <postmaster at pallmann dot com>
Date: 18 Mar 2008 23:42
Subject:
To: apt dot get at gmail dot com

This is an automatically generated Delivery Status Notification.

*** ATTENTION ***

Your email is being returned to you because there was a problem with
its delivery.  The address was undeliverable or the user was unknown.
The reason your email is being returned to you is listed below.  Please
direct further questions regarding this message to your local email
administrator or internet service provider.

-Postmaster


   ----- Transcript of session follows -----
... while talking to smtp.pallmann.com.:
<<< 550 MAILBOX NOT FOUND
555 <pallmann.com>... User unknown
Reporting-MTA: dns; mailhost.pallmann.com

Final-Recipient: RFC822; pallmann.com
Action: failed
Status: 5.1.1
Remote-MTA: DNS; smtp.pallmann.com
Diagnostic-Code: SMTP; 550 MAILBOX NOT FOUND
Last-Attempt-Date: epoch (EDT)