TroopWebHost makes it easy to send messages to a group.
From the Patrols page you can send a message to the members of a patrol.
From the Dynamic Subgroups page you can send a message to the members of a dynamic subgroup.
In similar fashion you can send to the members of an E-Mail Group or a Venturing Crew.
You can also send an e-mail to the participants of an event, or send an invitation to the undecideds.
The Send E-Mail To Group page on the E-Mail menu lets you send a message to any of these groups, starting from one convenient page.
As shown below, it lists all of the different types of groups to which you can send a message, with a button next to each group name to initiate the message.