It seems to me that opening a new mail buffer to compose or reply, then changing your mind and deciding to kill that buffer, should not prompt to save a modified buffer.
Of course org-msg inserts org properties (and optional possible greeting+signature) when opening the mail buffer, so I understand why the behavior occurs, but this doesn't really count as editing that the user might want to save. I've been using a simple fix for this locally and will send a pull request.
It seems to me that opening a new mail buffer to compose or reply, then changing your mind and deciding to kill that buffer, should not prompt to save a modified buffer.
Of course org-msg inserts org properties (and optional possible greeting+signature) when opening the mail buffer, so I understand why the behavior occurs, but this doesn't really count as editing that the user might want to save. I've been using a simple fix for this locally and will send a pull request.