Many use uebimiau web mail (pop3 mail reader script in php) as web mail on web servers. uebimiau have not upgraded recently, it seems the author is busy with other projects and have no time to update this web mail script or make it better.
I found a PHP Webmail script that work just like
I spend some time in forum, there are users who upgrade from uebimiau to this new web mail script. I have not tested it, but from install instructions, it look similar to uebimiau web mail.
There are many free open source web mail scripts, but not all work with pop mail boxes, most use IMAP. Many using standard version of MailEnable mail server can only use pop3 mail readers like uebimiau or telaen.