It's beyond me why you want to replace one line of code with 5 lines of code (and you're going to use an external program anyway....), but here it is:

 
open my $fh => $file or die "Failed to open $file: $!\n";
open my $mh => "| mailx -s 'Title' email" or die "Failed to open pipe:
+ $!\n";
print $mh $_ while <$fh>;
close $mh or die "Failed to close pipe: $!\n";
close $fh or die "Failed to close $file: $!\n";
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With open STDERR, "/dev/null" you open the handle for reading. Try opening it for writing, using open STDERR, "> /dev/null"

Abigail