has_many at two levels

I am using Rails 2.3.5.

Company has many users. User has many emails addresses. Association tables are company_users and user_emails table.

I want to get all the email addresses for a company. What is the most efficient way to get that?

From stackoverflow

• In the definition of Company add the line:

  has_many :emails, :through => :users
  

  Now all Company objects have an emails method, which returns all the emails of all the users of that company.

• Try the following:

  has_many :emails, :through => :users
  

  Not sure if the association works on many-many-many, but it's worth a shot. The documentation can be found here.