This is a great history of email in some ways, but flawed due to omissions. While alot of the dates are true, email has been around longer than 29 years. And the number of email accounts is underrepresented.
A better history of email is here, Email – Wikipedia, the free encyclopedia. Still that article, Today is the 29th anniversary of email, as copyrighted by this man – Shareables, has this great infographic that is definitely worth sharing for the highlights it does mention.