I use Gmail and I would like to get a notification every time I receive an email. However, it seems that I have to use Thunderbird in order to get the notifications.
Is this correct, or are there other possibility to set things up in order to be warned when I receive a new email?
No, you can use a lot of other email clients like:
to get email notifications. There some more. The german Ubuntuusers Wiki has a nice list with email clients.
I think you'll like "Unity Mail," which you can install from the Ubuntu Software Center. Per the description, "It displays notifications about incoming mail, shows number of unread messages in the Unity Launcher and shows subjects in the Messaging Menu."
If you want notifications when a new email is received at your isp email server without having to keep an email client running I use Poppeeper running in WINE.
It's a windows program but it works very well in ubuntu using wine. It can be setup to check several email accounts at any interval you like. You have to install a plugin in poppeeper to display a notification bubble if you want a visual notification or you can leave it as a standard install and poppeeper will display a blue flag in the system tray at the top of the screen when a new email is received, you can then double click on the icon and it will open a screen where you can preview the incoming emails / delete unwanted ones even before you open up your email client.
I wouldn't be without it.
