Please note that development-related questions should be placed in the
Add-ins and Developer Information forum, if you want them to get the proper love...
As for your question, you could do so, assuming you can install PHP (not everyone has had the best success with this, and it's unsupported). You'll have to configure it to use an external SMTP server (e.g. your ISP's) though.
I'm not on the WHS team, I just post a lot. :)