I have gmail app on my Impression. Follow this tutorial and it will tell you how to get gmail app on your phone. The app is about 3/4 of the way down on the page.
http://www.samsung-impression.org/third-party-samsung-impression-software/applications-for-the-samsung-impression/Or you can install the widget and use it as a shortcut to gmail.com on your phones desktop. Follow this tutorial on how to install the widget. I have both App and Widget installed on my phone, don't ask me why I just do.
http://www.samsung-impression.org/samsung-impression-how-to/how-to-get-widgets-on-the-impression/If you need more help I will try to help as best as I can. GL
