Instead of sending out mass emails to keep people informed, please take advantage of some of the functionality built into CommunityServer. You can subscribe to forums in 2 ways (everyone should subscribe to the announcements forum), either by adding it to your RSS aggregator or by clicking the options button on the main page for the forum. On that options screen you can set to be notified via email of new posts to the forum.
This way everyone can stay informed on upcoming events and goodies that come our way.
Thanks