Type "mail" to see your mail in the console. Then you can simply type the number next to the subject to view that email.

I am also having trouble getting email on Outlook. The first step is to install Dovecot, but I am confused on where to go after that.

Be careful not to confuse setting up a mailbox and mail server on your linux host with configuring IMAP and POP access. Postfix is an MX server which will handle sending mail out and receiving mail and putting it into a maildir (mailbox) for you.

However, once that is setup, you'll want to setup an IMAP and/or a POP server in order to access that mail from Outlook. Look for a guide on how to install Dovecot and that should get you going.

If you're trying to setup a web host, I recommend looking into Virtualmin GPL. It's a free control panel extension (for Webmin) and is extremely easy to setup. Once setup there is a bit of a learning curve, but unlike many of the other free alternatives, "it just works".

This is what I used, up to the Horde part : http://www.exratione.com/2012/05/a-mailserver-on-ubuntu-1204-postfix-dovecot-mysql/

Works great, I can add users in PostfixAdmin and I check/retrieve all my email in Gmail (which means you can do the same, in Outlook).

What would be cool is if there was a preconfigure mail server image with instructions on how to setup the MX records.

Or have a place to share images.

I am working on it.
I am building a simplified postfix setup. It will include Dovecot without mysql, and one with it. That way should anyone want to chose a different account management, they are not stuck with mysql... which sucks balls.