[CentOS] Rejecting valid mail (including this mailing list)

Recently, I added the below line to my sendmail.mc and rebuilt.  
Everything was working just fine until sometime today.  In looking over 
the maillog, it seems if almost every piece of mail was rejected because 
of this configuration - mail that I know is OK, valid, and not a source 
of spam, like tamu.edu.  Not only that, but the mailing list from centos 
was being rejected as well.  Anyone know what might be happening?  One 
link I ran across said that ordb.org went out of business or stopped 
their service in Dec of '06.  If that's the case, why is their info 
still being listed in some of the sendmail configs, and others still 
advertising it's use.

dnl # FEATURE(`dnsbl', `relays.ordb.org', `"550 Email rejected due to 
sending server misconfiguration - see 
http://www.ordb.org/faq/\#why_rejected"')dnl

Sam