[ubuntu] Installing a mail server to use with a webmail client?

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http://ubuntuforums.org – Hello people, I just installed Ubuntu 12.04 and I also installed Apache2, PHP5, MySQL, PHPMyAdmin, vsftpd. Everything is working perfectly and it's very smooth and fast. My main goal however, is to setup a mail server so that I can send and receive mail using a webmail client such as squirrel-mail, afterlogic webmail, roundcube, atmail, etc... Now, on windows it's pretty simple...just install Hmailserver and install the webmail scripts via php and that would be it. But on Ubuntu I have no idea what to do. What are the steps necessary to install a mail server, so I can install my PHP mail sc (Hardware)