I am looking for an easy to install and setup email list.
like majordomo or mailman.

on my server it is there and works great,

my client's who has vdash control panel doesn't have any mailing lists.

I am trying to setup an email based list for their staff so they can sent mail to each other
at [][email protected][/]

thanks

I have some clients who use phpList.
http://tincan.co.uk/phplist

Not sure if it's what you need - I've not really used it.

Is it all done thu email as far as end user is concerned? or do they have to post via web?

phplist is pretty good. I used to use it, but now use autorsponse plus. It's more of an autoresponder, but works anyway. Phplist is probably your best bet.