So i use the app Gmail Notifier and one of the disadvantages of this app i think is that if i want open an email it opens my web browser is there anyway i can redirect the app so it opens emails in mail app not my web browser
I don't think so because it is linke to the gmail.com mailbox and not your local mail app. I use Growl with Growlmail. Works perfectly, the same as the notifier, except it notifies when mail comes into the inbox of my mail app and notifies from any of the three mail accounts I have. I like it better.
It shows a badge, but doesn't give you a little preview of the message which I like. I like to see who it is from and the subject in the pop up so I know if I need to switch over, say from a movie or something to reply or it can wait. Also, I noticed that the "bong" when new mail arrives in the mail app doesn't always sound, especially when listening to music or watching a video. So the Growl pop up is a perfect solution for me using the Mail App.
When I used Outlook 2011 it had the pop up notifier, but everything else about Outlook 2011 sucked so bad I gave it up and moved back to Mail with Growl. Plus you can use Growl for tons of other notifications from other apps too, it really is a cool little app.