Brent ‘Dax’ Royal-Gordon has created a registry hack for Windows users to register the official GMail notifier as the email application in Windows. He shared this in his note to me:

It’s a Registry patch to set Gmail (via the official notifier) to
appear as the e-mail app on the Start menu. As a side effect, “Google
Gmail” will appear in the list of e-mail apps in IE’s Tools | Internet
Options. Note that there are some hardcoded paths in there–including
one to Firefox, since there doesn’t seem to be a simple way to open
the default browser–but they shouldn’t be difficult to fix by hand.

A great little Windows hack. Plus, Brent is a Perl and Parrot hacker so it must be golden.

Source: GMail Registry Hack