You can do pretty much anything with Perl when it comes to manipulating Text. Using regular expressions will enable you to focus on the section of the "email" that you want and rip out the information that you're after.
After that it's simply a case of passing the variables to the PHP script, so really it's reliant on a couple of major things.
1. How the mail message gets to the Perl Script, and
2. How the PHP script will accept your input.
For example, are you simply running a PHP script and supplying the variables to STDIN, or do you need to send it as CGI data.
More information/source code examples/sample "mail messages" for parsing would make it much more likely that you can get some more relevant help.