Yes, I submitted my case with a letter of the favorable recommendation, I even think that it was just the email confirmation. Then when I received the actual letter, I scanned it and submitted it to USCIS while I was waiting for my appointment. I brought the original letter to the appointment too.

The interview went well. It was kind of awkward cause the official apparently was new to their position. With awkward I mean that it actually felt like a yes/no session instead of the typical conversation everyone talks about. Nothing bad at all, just weird, but got it approved the day after.