A mailing list is very easy using the cPanel interface. The first thing you need to do is log into your client area. Once you have logged in you will be able to then log into your cPanel account by clicking on the cPanel button next to the domain you wish to make the list for.
If you know your cPanel username and password (they would have been sent to you in your welcome email from Colosseum) you can also access your cPanel via www.yourdomain.com:2082.
Once in your cPanel click on the icon labeled "Mailing Lists" from here you can create a new mailing list or delete/change the password/log in to an existing list.
To manage an existing mailing list click on the modify link that shows to the right of the lists name. A new window will open up asking you to enter the List administrators password. From here you can do a variety of tasks including viewing the lists membership, send out invites to joing your mailing list, and changing other various options.
