Mail::Mailer sounds right for your first task here. Something like:

use strict; 
use warnings; 

use Mail::Mailer; 

# mfile == 'Mail File' in context
my $mfile   = "somefile.txt";

# Override the default mailer found when the module was
# installed (looks for 'mail', 'Mail' by default)
my $mailer = Mail::Mailer->new("mail", "/usr/bin/mailx");

$mailer->open('From'   =>'Joe User <juser@domain.com>',
              'To'     =>'Sally Seashells <ss@sshore.com>',
              'Subject'=>'Do you sell seashells by the seashore?');

open (MFILE, "<$mfile") or die "Cannot open file: $!";
print $mailer MFILE;
close MFILE;
close($mailer) or die "Cannot close mailer: $!";
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For your second task, you could always use something like this:

package Stderr;

sub new { 
        bless {}
}

# Turn off stderr
sub stderr_off {
        open(SAVEERR, ">&STDERR");
        close(STDERR);
}

# Turn on stderr
sub stderr_on {
        open(STDERR, ">&SAVEERR");
        close(SAVEERR);
}

1;
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