以下は動作しません
subject = "The amount of £#{@amount} has been sent to your account".html_safe
mail(:to => @email, :subject => subject, :reply_to => 'support@xyz.com')
どちらでもない
subject = "The amount of £#{@amount} has been sent to your account".html_safe
メールの件名にポンド記号を表示するにはどうすればよいですか?