Before we can start using mu4e, we need to tell Emacs to load
it. So, add to your ~/.emacs (or its moral equivalent, such as
~/.emacs.d/init.el) something like:
(require 'mu4e)
If Emacs complains that it cannot find mu4e, check your
load-path and make sure that mu4e’s installation directory is
part of it. If not, you can add it:
(add-to-list 'load-path MU4E-PATH)
with MU4E-PATH replaced with the actual path.