The simplest is to let users subscribe to Newsletters.
You can also subscribe groups to newsletters and let people join and leave groups with PluginSubscribeGroup. This is interesting if you want to use groups for other things. Ex. permissions, PluginGroup, etc.
You'll want to create a group for the Golf chairman to be allowed to send newsletters. Or you could make a group for all chairmen, and permit them to send newsletters to all groups, but with the understanding that they should only send to their own group.