Undelivered Mail Returned to Sender

[MAILER-DAEMON@xxxxxxxxxxxxxx (Mail Delivery System)]

This is an automated message from the BorderWare Security Platform
at host CNLG.GOV.AB.CA.

The message returned below could not be delivered to its 
intended
destinations.

For further assistance, please send mail to <postmaster@xxxxxxxxxxxxxx>.

If you do so, please include this problem report. You can delete
your own text from the message returned below.

Reason:

<bchapman@xxxxxxxxx>: host 142.229.229.10[142.229.229.10] said: 550 5.1.1 User
    unknown (in reply to RCPT TO command)

Reporting-MTA: dns; CNLG.GOV.AB.CA
X-BorderWare-Security-Platform-Queue-ID: 389A221B2222C7FD
X-BorderWare-Security-Platform-Sender: rfc822; kernprof@oss.sgi.com
Arrival-Date: Sun, 20 Apr 2008 06:27:12 -0600 (MDT)

Final-Recipient: rfc822; bchapman@gov.ab.ca
Action: failed
Status: 5.0.0
Diagnostic-Code: X-BorderWare-Security-Platform; host
    142.229.229.10[142.229.229.10] said: 550 5.1.1 User unknown (in reply to
    RCPT TO command)
> --- Begin Message ---
>
> --- End Message ---