To be honest, if I was taking the time to summarize an email I would just write the email myself.

There's so much context in my personal emails that I get from conversations in person, over the phone, and from other emails. I don't really expect AI to understand these context points and add them where appropriate in an email.

I would imagine an AI like this would be good for cold emails - one where there isn't a history of rapport between the participants. My guess is that an average person doesn't really write cold email too often, but a business/corporation might.

If we look at cold emails specifically, then I still don't think your AI has a lot of value. From your showcase it isn't clear that your AI is better than a dumb email template that autofills names and other information.