Can I invite non-users to join my board

Yes, non-MyBoard users can be invited to join your board and collaborate. They can be easily invited via email (Read more about managing users) in which an invitation to sign up to MyBoard will be sent to them. Once signed up they will automatically be added to your board. 

Note that you may need to ensure that your organization's security policies allow for collaboration with external users, and that you have the necessary permissions to do so.