It was a conversation between like minded friends and so the tone of each email was deliriously excited and informal. This is what I think newsletters crave to be.
Sure, this applies to newsletters, but this is just great general writing advice. My worst writing is always the product of over thinking and forgetting about you, the person reading this. I try to write the way I talk, and that just happens naturally when I write to my friend instead of writing to an “audience” (gross).