gmail as means for volunteer communication

I use gmail in the classroom as a means for me to communicate effectively with my parent volunteers.  I am able to create email contact groups based on the type of volunteering they do within my classroom.  For example, I have an entire folder of reading volunteers and we are able to email each other in a single thread with updated current information about what the reading students are working on and the educational progress that is being made.  My volunteers are able to communicate with one another easily through this single thread.  I am able to add new contacts to the folder with ease.