As you probably know, each Facebook account is given a Facebook email address, like email@example.com. When someone sends an email to your Facebook email address, you will receive the email as a Facebook message, available in your Facebook Messages tab.
But what if you want to send or receive emails, through Outlook or other email client, for your Facebook email address?
Well, that’s not possible. You simply can not connect your Facebook email address as a regular email account (POP, IMAP, etc) in Outlook or in any other email client applications, simply because Facebook does not offer such access to their servers.
At most, you can install the Facebook Social Connector for Outlook and get access to Facebook messages, inside Outlook. But you can’t compose new messages and you can’t send them as emails (like sending a message to firstname.lastname@example.org).
Unfortunately, the other way around is also not possible (using the Facebook Messages tab to send/receive real emails or adding your other email accounts to Facebook Messages).