ubuntu server pear not sending email no hints in log files

Question

I installed Ubuntu 12.04 as a KVM virtual machine host. I selected SSH and lamp. All work nice. I copy all the files from my old website to this new server to test. All work as expected but the email doesn’t work. I have a form where user types his/her email, click send and email is sent. This works in the old server. I make sure I installed all pear packages needed

sudo apt-get install php-pear sudo pear install mail sudo pear install Net_SMTP sudo pear install mail_mime

I changed the php.ini file so I can see any kind of errors. Then I looked on Apache log files for any kind of hint but nothing found. No errors no complaints.

Firewall is disabled.

Can anyone please tell me what would I need to do to enable Ubuntu 12.4 server send email using pear packages with php. Code works in Ubuntu 10.04 LTS.

note: This new server is a virtual machine. I has access to the internet and I can access it using http. Connectivity is not a problem.

I also noticed that I have these. Which php.ini file should I use?

find / -name php.ini /etc/php5/cli/php.ini /etc/php5/apache2/php.ini

Thanks for you help