https://support.apple.com/en-us/HT201607
Choose your default email application
Use these steps to choose which app opens when you click an email link.
Open Mail from the Applications folder, Dock, or Launchpad.
From the Mail menu, choose Preferences.
Click the General button.
Choose your desired default email application from the "Default email reader" pop-up menu.
Choose your default web browser
Use these steps to choose which app opens when you click a website link.
OS X Yosemite
From the Apple menu, choose System Preferences, then click General.
Click the "Default web browser" pop-up menu and choose a web browser, like Safari.
OS X Mavericks or earlier
Open Safari from the Applications folder, Dock, or Launchpad.
From the Safari menu, choose Preferences.
Click the General button.
Choose a web browser from the "Default web browser" pop-up menu, like Safari.