pi@raspberrypi:/var/www/html/test/mail $ tail -f -n 10 /var/log/apache2/error.log
sh: 1: /usr/sbin/sendmail: not found
http://www.codechewing.com/library/usr-sbin-sendmail-not-found-error-phpmailer/
http://muyraspi.blogspot.com.es/2013/06/enviar-mails.html