what we have?
iRedMail -> http://iredmail.com
Get the script over there. http://www.iredmail.com/download.html
Here we use ubuntu14.04 as server.
Just follow this tutorial:
http://www.iredmail.com/docs/install.iredmail.on.debian.ubuntu.html
F.Y.I. The version 0.9.0 of this software has already removed the phpldapadmin due to its lackness of security. MySQL or PostgreSQL is your friend. OpenLDAP works fine here mostly.
I would prefer PostgreSQL.
You should have knowledge about what hostname is, what those DNS records are if possible. Later you will have to do something about how to hook up one of your domain names to this site.
And also you should have some knowledge about how to make the mails sent from your server acceptable by others. That's an important part. Here's reference.
Setup DNS records for your iRedMail server
http://www.iredmail.com/docs/setup.dns.html
And
Configure mail client applications
http://www.iredmail.com/docs/index.html#configure-mail-client-applications
Those are very helpful.
Then it has 'roundcube' as the web Ajax client, iRedAdmin as the mail account client, Awstats as server log analyzer, and many more.
It is strongly recommended that you should have a SSL certificate.
Happy Hacking!