Mail and Yahoo Groups

This is my first post here and hope that I can find a solution to my problem.
I'm a member of a couple of Yahoo Groups. Whenever I attempt to send a message to another member, or to the group itself, Mail opens up as the default application. However, I use Outlook. Does anyone know how I can change my default email app from Mail to Outlook? The only way I can now communicate with my groups is via Web posts.
Any assistance is greatly appreciated!

Welcome to the Mac Forums.

In Mail preferences, choose General Tab, select Outlook as default email reader.
In Outlook's preferences, open the General Tab and select Outlook as default mail application.

Either way will work.