I store all mails local. I can share my setup. I will take a while for me to find time and collect things in the same place. I will report back to this comment.
+1 for local mails. I love it when I can open it offline and fast to read / write some long emails.
I'm not the OP but I have a similar setup. I keep my mutt [1] config in git, which is viewable publicly.