ActionMailer message delivery content

I have the ability to send email to a user if a certain user has requested interest in their product. In my email I want to include certain information that is pulled from users but at the moment I am getting errors because it states that they are undefined despite these lines being used elsewhere in my application. I shall copy the email below and anything between the <% %> is what I wish to include and was wondering if anyone could point me in the right direction and tell me which are those that are correct and are not. Any help would be wonderful. The message I want to send is as followed:

Hello <%@user.username%>

The user <% current_user.username %> has registered an interest in the following product of yours:

<% @book.book_name %>

The user <% current_user.usernames %> has the following games for offer:

<% current_user.book.book_name %>

To view <% current_user.username %> profile click <% link_to "here", current_user.show %> If you wish to contact the user by email then contact the following email <% current_user.email %>.

Below is my mailer class. I believe this is why it does not recognize the game command but I tried putting a similar line in as I had with user and it did not work. Any idess? My @user.username in the email works fine.

  class GameTrade < ActionMailer::Base     default :from => "Roger@gmail.com"

    def book_interest(user)       @user = user       mail :to => user.email, :subject => "book Interest"     end   end

My final problem is that I have been lead to believe that current_user does not work in the email delivery, how would I go about adding such feature or is it not possible?