mtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = smtp.gmail.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = yusetist, localhost.localdomain, , localhost, smtp.gmail.com
relayhost = mycorreo@gmail.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all

    #!/usr/bin/perl
    use Mail::Sendmail;
 
    my %mail = (
       From    => 'sanchezgarciatomas@gmail.com',
       To      => 'sanchezgarciatomas@gmail.com',
       Message => "Este es un mensaje muy cortito",
    );
 
    if(sendmail %mail){
       print "Mail enviado";
    }
    else{
       sendmail(%mail) or die $Mail::Sendmail::error;
    }

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = yusetist
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = yusetist, localhost.localdomain, , localhost
relayhost = 
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all

use Mail::Sendmail;
 
      $mail{smtp} = [qw(smtp.gmail.com)];
      $mail{port} = 587;
 
      %mail=(To => 'correo',
                   From => 'correo',
                   Message => "Mensaje de prueba"
            );
 
      if(sendmail %mail){
         print "Mail enviado correctamente.\n";
      }
      else{
         print "Error al enviar mail: $Mail::Sendmail::error\n";
      }

use Mail::Sendmail;
 
  print "Testing Mail::Sendmail version $Mail::Sendmail::VERSION\n";
  print "Default server: $Mail::Sendmail::mailcfg{smtp}->[0]\n";
  print "Default sender: $Mail::Sendmail::mailcfg{from}\n";
 
  %mail = (
      To      => 'correo@gmail.com',
      From    => 'correo@gmail.com',
      Bcc     => 'Someone <correo@gmail.com>, Someone else her@there.com',
      # only addresses are extracted from Bcc, real names disregarded
      Cc      => 'Yet someone else <correo@gmail.com>',
      # Cc will appear in the header. (Bcc will not)
      Subject => 'Test message',
      'X-Mailer' => "Mail::Sendmail version $Mail::Sendmail::VERSION",
  );
 
 
  $mail{Smtp} = 'smtp.gmail.com';
  $mail{'X-custom'} = 'My custom additionnal header';
  $mail{'mESSaGE : '} = "The message key looks terrible, but works.";
  # cheat on the date:
  $mail{Date} = Mail::Sendmail::time_to_date( time() - 86400 );
 
  if (sendmail %mail) { print "Mail sent OK.\n" }
  else { print "Error sending mail: $Mail::Sendmail::error \n" }
 
  print "\n\$Mail::Sendmail::log says:\n", $Mail::Sendmail::log;

Testing Mail::Sendmail version 0.79_16 
Default server: localhost
Default sender: 
Error sending mail: MAIL FROM: error (530 5.7.0 Must issue a STARTTLS command first. g15sm4632205wiv.22 - gsmtp
)
Server said: 530 5.7.0 Must issue a STARTTLS command first. g15sm4632205wiv.22 - gsmtp
 

$Mail::Sendmail::log says:
Mail::Sendmail v. 0.79_16  - Sat Jun 27 23:52:46 2015
Date: Fri, 26 Jun 2015 23:52:46 +0200
Server: smtp.gmail.com Port: 25
From: correo@gmail.com
Subject: Test message

use Mail::Sendmail;
 
      $mail{smtp} = [qw(smtp.gmail.com)];
      $mail{from} = 'correo@gmail.com';
      $mail{port} = 587;
 
      %mail=(To => 'correo@gmail.com',
                   From => 'correo@hotmail.com',
                   Message => "Mensaje de prueba"
            );
 
      if(sendmail %mail){
         print "Mail enviado correctamente.\n";
      }
      else{
         print "Error al enviar mail: $Mail::Sendmail::error\n";
      }

Error al enviar mail: connect to localhost failed (Conexión rehusada)
connect to localhost failed
connect to localhost failed (Conexión rehusada) no (more) retries!