action_mailer.default_url_options not used in named routes within mailer view ?

In my mailer view I have a named route :

accept_user_invitation_url(@resource, :invitation_token =>
@resource.invitation_token)

In my routes :
accept_user_invitation GET /users/invitation/accept(.:format)
{:action=>"edit", :controller=>"users/invitations"}

in development , I set
config.action_mailer.default_url_options = { :host => 'lvh.me' , :port
=> 3000}