The internal Zend Studio debugger does not support i5/OS functions. The way to use Studio for i5/OS with your i5 is to use Remote Debugging.
The way to use Studio for i5/OS with your i5 is to use Remote Debugging. This will allow you to compose a script on your PC and run it in Studio using the php engine running on your i5. You will need to do this to access the i5 Toolkit Functions such as i5_connect(), as well as the ibm_db2 extensions, such as db2_connect().
The PHP mail() function is used to send emails from inside a script.