Note, Emacs bookmarks are not to be confused with mu4e’s bookmarks; the former
are a generic linking system across Emacs, while the latter are stored queries
within mu4e.
mu4e supports linking to the message-at-point through the normal Emacs
built-in bookmark system. The links are based on the message’s message-id, and
thus the bookmarks stay valid even if you move the message around.