#!/bin/sh

perl -i~ -e '  # -i~ for in-place editing with tilde backup
  use strict;
  use warnings;
  my %excludehash;
  my $file = shift;
  open(my $excludelist, "<", $file) or die;
  while(<$excludelist>) {
    chomp;
    next if /^$/;
    $excludehash{ $_ }=1;
  }
  close($excludelist);
  {
    local($/) = "";
    while (<>) {
      next if ( m/^YOURKEY:\s+(.*)$/m && $excludehash{ $1 } );
      print
    }
  }' "excludefile" "datafile"