Wordpress plugin V2.3.3.

How can I capture the email addresses of the visitors who use the plugin?

When people use the plugin on my site ( http://software-integrity.com/blog/ ), they have to enter their email addresses, naturally, to get the PDFs sent to them. How can I get hold of these email addresses and store them? As an embedded software engineer, I am not a PHP expert, but I can patch the code if you tell me roughly how and where I should do it. I already looked at the code but the solution did not present itself to me! I hope you can help. Thank you very much for an excellent plugin. Peter Bushell, Director, Software Integrity Ltd.

Answers to question on topic: Wordpress plugin V2.3.3.