@DavidofDeLand -- While I appreciate the concerns you share in your post, it saddens me that you assume group tree-mails would be used to foster division rather than community.
Has that been your experience on other sites?
I've been part of several group tree-mails here on ATP. If I'm not mistaken, it was a group tree-mail that created the "welcoming committee" for new users here. It was a group tree-mail that resulted in a group baby gift for Trish.
Group tree-mails can also be used to talk about stuff that is 1)unrelated to gardening and thus not relevant to ATP, and 2)more personal than we are willing to share on a public forum.
So rather than fostering division, group tree-mails can easily further the sense of community amongst members here.
And my own personal experience has proven that to be the rule, at least in the group tree-mails I've been part of.
