To set Mailbird as your default email client:
1) Go to the Mailbird menu in the top left corner of the main window.
2) Select "Settings"
3) Click the "Advanced" tab
4) Check or un-check "Default email application: Tell me if Mailbird is not the default email client"
5) Click the "Set as default" button
Now anytime you click on an email link a compose window will automatically open in Mailbird for you. We've also added MAPI support for Mailbird 2.0, this will enable you to send a file directly through Mailbird.