I am working with Magento 1.9.2 and send email to a friend is not sending emails. It gives sent successfully report message. But not sending. Any clue how to debug?
Check you've got postfix installed and make sure you've configured it. Otherwise check IPTables to ensure you've not got an outbound drop rule that's not allowing if out.
Check IPTables with
iptables -L if that has no rules then please share with me your post fix configuration.
Also check the service via
service postfix status