Standard lamp stack php mail() returns true but nothing is sent

I know I must be missing something simple. The php function mail() returns true but I never receive the email. I looked at another similar question but when I tried running

sudo /opt/bitnami/php/bin/pear install pear/Net_SMTP pear/Mail-1.2.0

I received an error:

/opt/bitnami/php/bin/pear: command not found

I was hunting through the filesystem and could not find any php directory in that location (hence the error)

What am I missing?

Here is whats in /opt/bitnami/ - as you can see, no PHP