If you haven't used the new hidden group feature to hide some of your groups, you might want to consider it. This new group type allows you to create a group that can't be seen and therefor emailed by anyone other than an admin. So for instance if you have an "all users" group to share standard documents with everyone you might wnat to consider hiding it. This way, nobody can just decide to send an email to everyone on your site.
You can read the details about this group and the other two group types here:
In a site level, private or hidden group the members can only be seen by site administrators and the owner of the group. In a project level private or hidden group the members can be seen by the site administrators, groups owners, and project administrators with access to that project. Private and hidden groups are distinguished from general groups by a different icon. A private or hidden group cannot be expanded unless you are the owner of the group or are a site administrator.
Open group — the group and its members can be seen by everyone who has access to the same projects.
Private group — the group can be seen by everyone. However the members of the group can only be seen by site administrators, the group owner, and project administrators associated with that project (if a project level group).
Hidden group — the group and its members cannot be seen by anyone except site administrators, the group owner, and project administrators associated with that project (if a project level group).
In a private or hidden group, members of the group cannot see each other's name or contact information. Private and hidden groups can be created by site administrators and project administrators (who have the privilege to create members and groups). Project administrators can edit and delete groups that have been defined for thier project. Group owners can edit and delete groups that they own. Site administrators can edit and delete all groups.
When used in conjunction with the deposit permission, a private or hidden group is useful if you want members to be able to update project files but you don't want them to see who else is updating documents. For example, if you are asking members to bid on a project, you want them to be able to add a document detailing their bid, but you don't want them to see who the other bidders are, or their contact information. Thus, creating a private or hidden group, used in conjunction with the deposit permission, allows you to do this. Private or hidden group members can add a document to the project, but they can't see other documents in the project nor can they see who the other members in the group are. Note that they can still see other project members, but not the other members of the private or hidden group.
When sending email through Buzzsaw, a private or hidden group is automatically placed in the BCC field. This prevents the names and email addresses from being exposed to other mail recipients. It is not recommended that you assign a form to a private or hidden group. Doing so exposes the names and email addresses of private or hidden group members in the routing tab of forms and in various dashboards. When a private or hidden group is added to a discussion only the group name is displayed in the participants field.
Limitations of Using Private and Hidden Groups While a private or hidden group can be an effective way of maintaining confidentiality, there are limitations. The member names of a private or hidden group do appear in certain places across the site (such as a document's author). In order to maintain confidentiality within the private or hidden group, you must give each member deposit permission. In this way, when a document is added to a project, the private or hidden group members can not see the document or the author. The author's name can be seen by members who are not in the private or hidden group.
It is also recommended that you do not assign a form to a private or hidden group. Doing so exposes the names and email addresses of private or hidden group members in email notifications. Forms can only be assigned to hidden groups by administrators of the project containing the form log.
No, I'm not talking about Zelda. I'm referring to the ability to link files to forms in Buzzsaw Professional. We had a release a while back that included this great enhancement and I wanted to make sure everyone knew about it and what it offered. 
