Approaching Angels by E-Mail - How much information should I expose?

I consider contacting a few potential angel investors through E-mail, for my yet to be founded startup.

My Executive Summary is ready to be sent, but I'm wondering if its safe to send it right away, or even if I should send even more information such as application mock-ups. Our executive summary and mock-ups pretty much uncover many aspects of our application that we would like to keep confidential from potential competitors.

Moreover, I've been wondering if sending just the executive summary (4 pages), would be good attractive enough as it is quite a read (although interesting, I believe), and maybe without no visual information (mock-ups/video) we will discourage our potential investors.

By the way, we already have a very basic prototype active (Mobile app) with some active users as well (Less than 100). But it doesn't contain any of the "killer features" that are going to be in the final version we aim for.

Think from the perspective of the person you're contacting. You're receiving a 4-page executive summary, from an unknown person, who is essentially asking for money. And of course, if you're known to be an angel investor, you probably get dozens of such emails per week. What do you think an angel investor in this situation would likely do: I think your executive summary wouldn't even make it past the spam filter. Besides, people don't want to read long emails, especially coming from strangers.

So if emailing potential investors is your strategy I'd reconsider your approach. I'd simply write something much much shorter, with no attachments, and I'd lower the bar with the goal of only getting back an initial reply that could open a door. "Hi,
I found your contact information on X. I wanted to get in touch with you because I'm creating a company. In a nutshell, I'm building a X for X target market (your description at this point should fit in a few words!!). I was wondering if you were currently looking to make investments in that space and if you wanted to discuss my plan further. Please let me know.
Thank you." I think this might give you a shot and that anything longer won't. But of course, that's just my opinion.

Good luck.

In my current company we have over 50 angel investors. When was the last time you gave tens of thousands of dollars of your own money to someone who sent you an e-mail? Exactly!
Figure out which angel groups invest in your type of business, find out how others got in front of them (many entrepreneurs will tell you), befriend some folks who already took their money, and get an introduction that way.
Just don't expect a dime with shortcuts. Raising angel round is actually harder, since they are writing you a check out of their own personal funds, not OPM (other people money) like VCs do.