What was the purpose of the commitees of correspondence?
"Samuel Adams and other colonial started with group,called Committees and Correspondence"
Correspondence is the plural form of correspondence when it is used as a collective, like, "Here's all my correspondence from Laura." However, when you are talking about different kinds of correspondence, or when counting, it would be correspondences, as in, "I've had thirty seven correspondences with Laura."
Mostly because many of the committees address issues that require a large amount of very specific knowledge, and it's unreasonable to hope for the entire governing body to achieve that level of knowledge. As such, commitees are formed and chaired, and the commitees report back to the main body politic -- at least that's the idea.
The main principle of business correspondence is to communicate clearly to the addressee. Another principle of business correspondence is to appropriately represent the organization and person sending the correspondence, that is, to make sure they are represented in a professional, businesslike manner.