According to PC Magazine (PCmag.com), Webmail means an Internet based e-mail program that users can use ffrom any computer worldwide. There are many web based e-mail software such as Squirrelmail, Ilohamail, Overlook, jawmail.org and many more.
I would like to target your attention to one of them – RoundCube. The reason is that the program is free and looks very friendly to use.
It is a multilingual IMAP client that comes with MIME support, address book, folder manipulation, and spell checker. It also allows search within the messages received. RoundCube uses PHP and works with MySQL database.
The other good thing is that it is skinnable using XHTML and CSS 2.
RoundCube Webmail works under the GNU General Public License. So anyone can use it and deploy it as well as re-distribute it.
Some of the web hosting companies that offer RoundCude are HostColor.com with its , Site5.com, HostGator, icukhosting.co.uk, Unitedhosting.co.uk, Stormweb.ie.