my @cur_admin_lines = do {
   open(my $fh, '<', $curAdmins)
      or die("Unable to read list of admins ($curAdmins): $!\n");
   <$fh>
};

##</code><code>##

my $cmd = "echo \"$msg\" | mail ...";
system("$cmd");

##</code><code>##

my $cmd = "mail ...";
open(my $fh, '|-', $cmd)
   or ...;
print $fh $msg;
close($fh);