Juan,

It is difficult to read your code when it is not formatted for this website. Could you please wrap your code in code tags, like: <code></code>?

I have made an attempt to reconstruct your code from what you have provided. I think your code looks like this, but please verify:

#!/usr/local/bin/perl 

# Program to check /var/log/messeges for alerts contining the word IDS
+ and send mails 
# in case the word is found- including the line 

use strict; 
use warnings; 
use Mail::Mailer; 

open (INFO, "/var/log/messages"); # Open the file

while { @message = <INFO> / IDS/g 
# Read it into an array 
@message = $& 

$mailer = Mail::Mailer->new("smtp", "10.83.27.71"); 
$mailer->open( 
  'From' => 'Syslog <syslog@hpda.com.ar>', 
  'To' => 'gabriela pinado <gabriela.pinado@hpda.com.ar>', 
  'Subject' => 'PiX Detected Attack '
); 

print $mailer <<@message; 
close($mailer) or die "can't close mailer: $!";
[download]

Here is my revised version:

#!/usr/local/bin/perl 

use strict; 
use warnings; 
use Mail::Mailer; 

my $mailer = Mail::Mailer->new("smtp", "10.83.27.71"); 

open (INFO, "/var/log/messages"); 

while (my $message = <INFO>) {
  next unless $message =~ / IDS/;

  $mailer->open( 
    'From'    => 'Syslog <syslog@hpda.com.ar>', 
    'To'      => 'gabriela pinado <gabriela.pinado@hpda.com.ar>', 
    'Subject' => 'PiX Detected Attack '
  ); 

  print $mailer $message; 
  $mailer->close() or die "can't close mailer: $!"; 
}
close INFO;
[download]

From what I can tell, I think this should have the desired result you are looking for.