SurgeMail is supplied with DList - a fully featured mailing list server. Mailing lists are administered via "Mailing Lists" on the main SurgeMail Web Admin interface.
Generally the Sysadmin would set up a list, and then users would send an email to the 'listname-request' address to 'subscribe' themselves to the list.
Users only interact with the list by sending emails either directly to the list to be 'posted' or to the listname-request address if they wish to join the list or send it commands. When users join the list they are normally sent this list of commands so that they know what the list can do for them.
The administration of mailing lists is fairly self explanatory, but if you run into difficulty or want to modify the dlist config files by hand here is the detailed DList manual
Users can create and manage their own mailing lists via the web user self management interface, see the g_user_list_quota, or user_list_quota settings and also the g_user_access setting for how to enable/disable this feature.
Anonymous access to mailing list archives is available if the mailing list has it's web_archive setting set to true. The url is http://localhost/list/<listname> (where listname is the name of the mailing list that has a message archive). This interface allows searching of the messages and for people to subscribe and unsubscribe. The "join_cookie true" or "list_join moderator" is recommended to stop users signing other people up to mailing lists.
A bulletin is just like a mailing list message sent globally to all users or all users of a domain but much more efficient. A nice feature of bulletins is that they will be delivered upon account creation to accounts that do not yet exist.
SurgeMail / WebMail supports two kinds of bulletins.
SurgeMail bulletins can be sent from the domain page in the Web Admin interface and will be delivered to all users with an Email account on SurgeMail. Of note is that these bulletins will be delivered in the WebMail inbox as an email message.
WebMail bulletins are slightly different. These are sent using the WebMail Web Admin interface and will only be delivered to WebMail users as a message in the bulletins folder.