As Rabbit said, this is an issue with the Default Program that is set.
For the most part, the Quick Access button's work off a combination of software/defaults.. If it has a browser button, it will generally open the Default browser, same with for e-mail. However, if it comes with software and the buttons are customizable then you can change it via the software.
More then likely it is due to the Default Program for E-mail being changed.