```ruby
module ActionMailerWithRequest

  module ControllerMixin

    def self.included(base)
      base.class_eval do
        before_filter :store_request
      end
    end

    def store_request
      Thread.current[:request] = request
    end

  end

  module MailerDefaultUrlOptions

    def self.included(base)
      base.class_eval do
        # Extends ActionMailer#default_url_options capabilities
        # by merging the latest request context into the default url options.
        #
        # Returns the default url options Hash.
        def default_url_options_with_current_request(*args)
          host = Thread.current[:request].try(:host)
          port = Thread.current[:request].try(:port)
          defaults = {}
          defaults[:host] = host if host
          defaults[:port] = port if port and port != 80
          default_url_options_without_current_request(*args).merge(defaults)
        end

        alias_method_chain :default_url_options, :current_request
      end
    end
  end
end
```

Use a String for better performance
user
```ruby
module ActionMailerWithRequest

  module ControllerMixin

    def self.included(base)
      base.class_eval do
        before_filter :store_request
      end
    end

    def store_request
      Thread.current[:request] = request
    end

  end

  module MailerDefaultUrlOptions

    def self.included(base)
      base.class_eval <<-RUBY, __FILE__, __LINE__ + 1
        # Extends ActionMailer#default_url_options capabilities
        # by merging the latest request context into the default url options.
        #
        # Returns the default url options Hash.
        def default_url_options_with_current_request(*args)
          host = Thread.current[:request].try(:host)
          port = Thread.current[:request].try(:port)
          defaults = {}
          defaults[:host] = host if host
          defaults[:port] = port if port and port != 80
          default_url_options_without_current_request(*args).merge(defaults)
        end

        alias_method_chain :default_url_options, :current_request
      RUBY
    end
  end
end
```
assistant