You need to provide enough information to convince the investor that it's worth her time to meet. There are startups that can do this in one sentence ("I sold my last startup $2b..."), but, for most, it's simply not possible.
The email should have a good subject and opening 1-2 sentences which piques her interest enough to keep reading. If you start by clearly and succinctly saying who you are, what you're doing (without any jargon or buzzwords), and why it's a fit for her firm, there's a good chance she'll continue reading a page long email.
The email should have a good subject and opening 1-2 sentences which piques her interest enough to keep reading. If you start by clearly and succinctly saying who you are, what you're doing (without any jargon or buzzwords), and why it's a fit for her firm, there's a good chance she'll continue reading a page long email.