This perl script will bulk remove emails from the Postfix mail queue based on a keyword, email domain, or email address.  The script came from this blog post:

#!/usr/bin/perl

$REGEXP = shift || die "no email-adress given
  (regexp-style, e.g. bl.*\@yahoo.com)!";

@data = qx</usr/sbin/postqueue -p>;
for (@data) {
  if (/^(\w+)(\*|\!)?\s/) {
    $queue_id = $1;
  }
  if($queue_id) {
    if (/$REGEXP/i) {
      $Q{$queue_id} = 1;
      $queue_id = "";
    }
  }
}

open(POSTSUPER,"|postsuper -d -") || die "couldn't open postsuper" ;

foreach (keys %Q) {
  print POSTSUPER "$_\n";
};

close(POSTSUPER);

Before running the script:

chmod 755 <scriptName.pl>

Example commands:

./<scriptName.pl> iamspammer.com
./<scriptName.pl> bogususer@mydomain.com
./<scriptName.pl> bush*\@whateverdomain.com
./<scriptName.pl> biz