I'm about to contact a potential PhD supervisor which has been suggested by my current masters supervisor. They should know each other very well since they've worked on multiple joint papers before. Currently, I have a recommendation letter from my masters supervisor but I don't know if I should provide it in the first Email. I don't know if recommendation letters are something the PhD supervisor would explicitly ask for later in the process or not.
So, is it a good idea to just blindly provide a reference letter on the first contact, hoping it would impress them more?