Here's another way (very similar to the first reply, but a little simpler):

#!/usr/bin/env perl

use strict;
use warnings;

my @message;

while (<DATA>)
{
    push @message, $_;
    if ( /quarantine/ ) {  # this is the last expected line of each me
+ssage
        local $_ = join( "", @message );
        local $\ = "\n";
        print if ( /<jay@/i );
        @message = ();
    }
}
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