Yes! A conjunctive relationship with basic email is one of the most attractive features of email2.
If you have adopted email2, you are in no way prevented from communicating with people who have not. Turning email2 "on" or "off" is simple. You can still create basic email messages through Outlook just as you always have, but if you'd like to create an email2 message in Outlook, you can do so by using the email2 Toolbar. Even if you do send someone who is not email2 enabled an email2 message, they can still read it: they are given an invitation to download and install the email2 Toolbar, OR they can simply access the message via the email2 Web Client.
// Edited July 2008