Paging Level3 Mail Admins: Your messagelabs config is broken

Note: sending this from my personal account to increase odds of someone seeing it. My work address is dmahoney@isc.org.

ISC is having trouble mailing noc@level3.net, we keep getting redirected to a messagelabs error, seems to be happening from any address we send from, including personal addresses and the (sender/envelope) address of our ticket system.

This is probably nonoptimal.

You can reach me voice at 650-423-1362, or our noc number at 650-423-1310.

Final-Recipient: rfc822; noc@Level3.net
Original-Recipient: rfc822;noc@Level3.net
Action: failed
Status: 5.0.0
Remote-MTA: dns; cluster5.us.messagelabs.com
Diagnostic-Code: smtp; 553-Sorry, your email address jtl@isc.org has been
553-blacklisted. Refer to the Troubleshooting page at
553-http://www.symanteccloud.com/troubleshooting for more 553
information.
(#5.7.1)

Sep 19 23:32:58 amstel postfix/smtp[93402]: ED44E1FCBC3: to=<noc@Level3.net>, relay=cluster5.us.messagelabs.com[216.82.250.51]:25, delay=6.6, delays=1.4/0/5.1/0.16, dsn=5.0.0, status=bounced (host cluster5.us.messagelabs.com[216.82.250.51] said: 553-Sorry, your email address dmahoney@isc.org has been 553-blacklisted. Refer to the Troubleshooting page at 553-http://www.symanteccloud.com/troubleshooting for more 553 information. (#5.7.1) (in reply to RCPT TO command))

-Dan Mahoney
(hat: isc.org operations group).