Under the covers: PRPC using the JavaMail API to send out emails over SMTP.
You could use this to send out HTML emails that contains buttons/links; but I suspect you mean the 'Outlook' style voting buttons here; in which case - you will have to use a third-party library in order to generate these.
I haven't used this myself - so I can't vouch for the library : but I found this third-party forum link which provides some information about a Java Library which list voting-buttons as one of its features : JTNEF.
It should be possible therefore to download this JAR (or JARs?), upload to PRPC and build a custom solution for this : again - I haven't tried this, so can't provide confirmation of easy or difficult this would be to achieve in practice.