Set the Default Browser and Email Client in Ubuntu
Ubuntu has a simple way to configure the default browser and mail client. Of course, Firefox is the default application for web browsing, so you shouldn’t ever need to use this screen, but if you insist, here’s how to do it.
Navigate to System \ Preferences \ Preferred ApplicationsHere you can specify which application you want to use for web or email links. For instance, if you are using Thunderbird for email instead of evolution, you can change that setting here.